Re: Very open-minded
girls in particular will rail against school uniforms and the imposed "uniformity"
I dare say there's ample evidence, including methodologically-sound ethnographic and sociological studies. to show this is not, in fact, a behavior particular to any demographic.
And yet, when they go out as groups, it's not uncommon to a group of girls wearing their own self-imposed "uniform", ie all wearing very similar clothing styles.
There are academic disciplines which had studied this phenomenon at some length, such as Cultural Studies, particularly in its original UK incarnation.1 Or cultural anthropology (Douglas's famous Purity and Danger being one prominent example). Or Critical Theory in the mode of the Frankfort School. Or ethnography (which is sometimes a branch of anthropology, sometimes a type of inquiry or set of research protocols under some other discipline) – I note a few ethnographic studies of teenagers' clothing choices.
Of course, teens are typically under a complex set of strong social pressures, and labor under the combination of a certain amount of personal freedom on the one hand, but numerous constraints that adults are usually free of on the other. And they have immature frontal lobes, which reduce their ability to moderate their emotional responses (relative to neurotypical adults, though certainly many of the latter suck at it too). So their decisions may not always be entirely rational.
And, of course, behavioral economics have shown that people most often assign large weights to immediate and intangible factors when making decisions anyway. Most decisions do not take long-term consequences, and certainly not logical consistency, into account.
In any case, culturally speaking, teenager behavior is something of a self-fulfilling prophecy. The category of teenager is a recent invention – only about a century old – and popular culture assigns all sorts of confrontational attitudes and behaviors to it. Teenagers are routinely urged by mainstream culture to "act out".
1Cultural Studies in the US became rather more diffuse and often less rigorous, and shows less of a focus on identifying and investigating particular subcultural groups and their relationship to mainstream culture. See Pfister, "The Americanization of Cultural Studies".