Sure, that's incredibly easy.
Heterosexual identity is the internalized idea that there is something fundamentally distinctive about you because you feel sexual desire exclusively for members of the opposite sex, and thus that you represent a different class of human being than people who do not exclusively experience sexual desire for the opposite sex, or who experience no sexual desire at all.
I doubt many hetrosexual people will have the sense that there's something "fundamentally distinctive" about them.
You can feel however you want about being a heterosexual, but it won't change the fundamental understanding you possess that you are (or are not) a heterosexual. That state of understanding yourself as a distinctive class of person called a heterosexual is heterosexual identity. It is not universal, it has not always existed, and it is not in any way required in order to have sex with the opposite sex.
Again, I don't buy the "distinctive class" thing.
Regardless of the term's origins, or any alternate term you use, most people, heck, most animals, are going to have an opposite-sex attraction. There isn't anything inherently right or wrong with any of that, just as there's nothing wrong about being outside that bracket, but again, defaults.
Now in practice, there's some baggage which come along with this. In most societies, the desire for vaginal intercourse between men and women is more normalized and tolerated than some other forms of sexual desire. Because heterosexuality is set up in opposition to all non-conforming sexual identities, it demands certain standards of purity. Heterosexuality is a status which, if you aren't careful, you can easily lose by thinking, saying or doing the wrong thing. Because heterosexuality requires that sexual desire be felt exclusively towards members of the opposite sex, it also requires that the sexes are understood as clearly intelligible and distinct from each other.
Again, disagree. Your argument seems to be purely on the level of identity.
I can state something along the lines of "man, John Doe, he's so hot," and get some eyebrows raised, that doesn't change anything about me as a person, or as far as sexual preference goes. Obviously there's stigma involved, but that doesn't change sexual preference. I don't become non-male every time I watch My Little Pony, and I don't become not-straight every time I write a same-sex romance. Absolutely there'd be some level of stigma with both for a variety of reasons (including age), it doesn't change my sexuality, nor would it change anyone else's.
Finally, there are the stereotypes. There are a lot of things that are distinctively recognizable as heterosexual, not for any definitive reason, but simply because of the history of heterosexuality as a concept and its relationship to other sexual identities. For example, the idea that sex is something men do to women. That concept goes right back to the patriarchal origins of heterosexuality, and it's still there. Pretty much any time heterosexuals (especially heterosexual men) try to talk about their own sexual experiences, you'll see this idea crop up in some form. Not always, but on the rare occasion it doesn't it's often a source of shame or humiliation for one partner or the other.
Yes, stereotypes. Stereotypes exist. They also exist regardless of facts. I can stereotype people all I want, none of that changes the facts on the ground. Stereotypes are a separate discussion from the facts on the ground, and you can see earlier in the thread about the facts.
Also, I actually do know what you mean about the idea that sex is something men do "do" women, but that's it. An idea, and one that's generally frowned upon. I hate to bring up the "lived experience" argument, but I've never metanyone in real life who braggged about "doing" someone. Maybe we live in different circles, but in my experience, people don't discuss their sexual experiences at all, and the one time a friend of mine did, he mentioned how it was "terrifying" (in that he'd just got married, first intercourse with wife, etc.). I don't recall how it came up, but it wasn't dwelled upon. People's sex lives are none of my business.
What you seem to be describing is what I'd call "bro culture," not "heterosexual culture."
I don't think that's something most people think about. It's definitely not something I thought about seeing the film for the first time as the disgusting little human larva I was. But I did know on some level that the scene was weird, and part of why it was weird was the fact that it was somehow extremely out of line with the other (heterosexual) media on which I had built my developing sexuality.
Like, the magic cake pussy bomb scene. 100% hetero. Zee and Link's relationship. 100% hetero. Morpheus' sexual tension with Niobe. 100% hetero. Persephone being jealous and blackmailing Neo into making out with her. 100% hetero. All obvious. Mostly gratuitous. All passed by the audience without a moment of thought (although.. maybe the first one).
But no, this scene is where the straights are being pandered to. We know because the straights noticed they didn't like it.
You might say that these things are 100% heterosexual, but they aren't presented in the same way, nor do they have the same narrative purpose. But since you brought them up (and when I list this, keep the Neo and Trinity stuff in mind
-Magic Cake: When I first saw it, I thought he was giving her diorhhea, and looking at YouTube comments, I'm clearly not alone there. But the scene is bereft of any actual intercourse (that we see), and from a character standpoint, it establishes the type of person the Merovingian is, and the fractured relationship he has with Persephone. From a thematic standpoint, it ties into the choice vs. control motif. Furthermore, through worldbuilding, it establishes how things work in the Matrix (it raises questions as to whether this is something programs do reguarly, in order to keep bluepills under control), and it kind of hints at some kind of elitism. The Merovingian mentions (parahprased), "it's what separates us [programs] from them [bluepills]". Which wouldn't be the first time we've seen programs display contempt for humans (see the agents for example). There's far more going on in the scene than just "cake gives woman orgasm."
-Zee & Link: This barely belongs in the discussion. Zee and Link are an item. Yes, and? Is "pandering" simply the depiction of relationships? Regrettably, I've seen the argument applied to same-sex relationships, where their mere presence is decried by idiots as a form of "pandering," but Zee and Link are new characters, so unlike Neo and Trinity, Reloaded establishes a dynamic between them, and it doesn't spend much time on them, nor does the movie just stop for intercourse.
-Morpheus & Niobe: For starters, I disagree that there's any sexual tension between them. Romantic, sure, but not sexual - the most intimate we see them is when Niobe hugs Morpheus in the third film. I'll grant you that the love triangle doesn't affect things that much, but I'd also argue that the film doesn't lose anything from it either. It never just "stops," in the way it does for the Neo/Trinity scene, and does add to Morpheus's character, given how it establishes he was kind of chill before going all-prophet. You could arguably read that as part of a character arc, in that it's when his faith is shattered in the third film that he and Niobe can be together again.
-Persephone: To claim she's 100% hetero is to ignore when she forces Niobe to kiss her in Enter the Matrix, but even confining this just to the films, to claim this is "pandering" is to ignore everything else that's going on around it. And I say that as someone who generally detests the scene. Yes, I get why it's here, but on its own? Bleh. But to establish what's going on:
1: It establishes Persephone's character. This works fine in terms of mythological reference - we have "Persephone," who's in a loveless marriage with a man who runs "Club Hel" - I'll let you fill in the gaps. But even that aside, it still ties in with the idea that programs don't really feel love, or at least, can't feel love, not anymore. She asks for a kiss from Neo, and only helps them after getting the "real" second kiss, because she's so starved for actual affection, and may not be capable of even having it anymore, in this version of the Matrix. Bear in mind, she doesn't just say "he (the Merovingian) was so different," but also "things were so different," a reference (in my view) to an earlier version of the Matrix when things were better off for everyone.
2: Everything I said above is relevant to the existence of Sati and her parents in the third film. We have one film (Reloaded) that shows that programs can't love or feel emotion in the same way as humans, then another (Revelations) where we see that programs CAN love each other (to Neo's amazement), but can produce offspring as well. It's no coincidence that in the very last shot, the Matrix has a golden hue rather than a green one, or that Sati is the one who makes the sunrise, or that Smith is the one who claims "only a human mind could invent something as inspid as love," yet it's a program born of love that's apparently in a position of power in Matrix Version 7. Not only is Smith wrong, he's part of the overall theme in the third film of humans and machines/programs being less distinct than they might think.
You could have the train station scenes without Persephone, yes, but it adds to the overall story and themes when you compare and contrast the two versions. Also, I understand that Sati and the names of her parents are relavant to Hindu mythology in the same way that Persephone is to Greek, but can't comment on that right now.
So, yeah. I disagree that the examples given are on the same level as Neo and Trinity having intercourse, because, as I've laid out before, the intercourse scene doesn't add anything. Not character, not theme, not worldbuilding, nothing. Whoever it's pandering to, if it succeeds in pandering or not, it doesn't change that IMO.
Also, fun fact, if you want a scene of what I WOULD call heterosexual pandering in the films that kind of works, take Thaddeus and June in 'Final Flight of the Osiris,' how each strike of their swords reveals more of their bodies. Does this serve anything? Not really. Is it pandering? Of course it is. Does it work? Well, I guess, a bit, but the fact that it panders better than Neo and Trinity doesn't change that it's still pandering. Hence why I find the scene eyerolling.