There's basically about as much caffeine in tea as in coffee, but because the caffeine from coffee is absorbed faster, it's gives a larger and faster "hit". But really, I don't think it's much about caffeine, because caffeine just isn't that potent. Well, maybe some of the really high octane energy drinks, plus all the other shit they shovel into it. They sell a vision to people to start their day with a bang, and that's a coffee or high energy drink to give people get up and go. And with a bit of luck for companies, get people started and maybe it becomes a routine. It is likely to be more psychological than it is pharmacological: the simple psychological association of a drink with energy makes people think they are more energetic.
This is also the shit about baristas. They are sold as artistans to give us the idea that the coffee is special, crafted: look at the effort that goes into it! In the same way, if you put food on an expensive plate and arrange it neatly, people think it tastes nicer. If you sell someone a $50 per metre gold-plated wire between their hi-fi and speakers instead of a basic copper cable, they're convinced the sound quality is better. It's a marketing trick. We all know deep down most of these baristas aren't highly trained artisans. Once you've poured an espresso shot into a pint of hot milk (especially if plus syrups, chocolate sprinkles), you may as well make the shot with instant coffee granules or just pour some out from a caffetiere. It's theatre. Like the sizing: medium, large, huge (so nothing is "small") and the stupid Italian words (medio, grande, venti or whatever it is) because the Italians are famous for coffee, despite the fact that an actual Italian would rather drink a litre of Venice canal water than a Starbucks. And whilst you're at it, you can also pick up a grotesquely overpriced and distinctly mediocre cookie, traybake or panini.