Because I am not a woman.
And?
So, are gendered bathrooms and changing rooms discriminatory as they are now, just concerning cis men and women? Are you of the belief that a straight man should be able to walk into a female changing area, and just hang out there?
The answer to this one is very complicated, but I'm going to try and boil it down to a question. It's a rhetorical question, because I think I already know the answer, and the answer is revealing.
Do you think that gay and bisexual women should be able to go into a female changing area?
I mean, let's break it down. Firstly, in general, regardless of who you are you shouldn't be hanging out in a changing room. It's a functional space which you should use for its intended function. If you're not changing, you shouldn't be in a changing room because it's a place where people go to get changed and having people just hanging out there could be disruptive.
So, assuming anyone in a changing room is actually changing, what's the problem with men and women changing in the same room? Why is that such a terrible problem? If it's based on the assumption that men will derive sexual excitement for seeing women changing, why does that not apply to gay and bi women, who are just as capable of being thirsty perverts as any straight man.
Again, rhetorical question. Because the answer is obvious. It's because men, in particular, cannot be trusted. It's because women spend their entire lives learning (correctly) that they have to fear men, and not just the ever-present possibility of unwanted attention or sexual violence from men, but also the male gaze. Men, conversely, spend their entire lives learning that women's bodies exist for their pleasure, that being able to look at women without their consent is normal and that women have an obligation to protect themselves from the male gaze. Again, queer women can be giant perverts, but they also don't register to other women as threatening, because they also implicitly know the rules.
The problem is that trans people, and even to an extend GNC men, are also sexually objectified by men, often in ways that are far less acknowledged or comfortable for the men involved and thus, in addition to being gross and unpleasant, are also more likely to provoke open hostility.
The problematic assumption here is that AMAB trans people are men who are putting on a façade or pretence. That is sadly how most people, even people who think they are trans inclusive, implicitly think about trans people. If you think like that, then there is no difference between allowing AMAB trans people into women's changing rooms, and allowing men. But that is not the discrimination. The discrimination is not that women's changing rooms are better, and that everyone has a right to be there. The discrimination is that both cis women and trans people have a need to protect themselves from men, but only one of those needs is recognized or met.
Again, the problem is men.
Like I said, it would take a miracle.
True, but some of us cannot fully relinquish the idea that men are equal human beings and capable of the same capacity for goodness as others, if they are properly taught and nurtured.
The alternative is not pleasant to think about, and would necessitate some pretty unpleasant solutions.
Like the myths of hate-crime gangs roaming the streets, just waiting to jump any LGBT person they see, especially in bathrooms?
Violence against LGBT people is largely opportunistic and "defensive". That's why the gay panic defence exists, because heterosexual men in particular seem prone to experiencing the existence of queer people as an attack on their identity. The simple fact is, "offending" a man is both inevitable and dangerous. Almost every queer person I know has experienced the outcome at least once. I've personally experienced it many times.