In my experiences (both state and private schools, in the UK) the problem with no uniform was that it marked you out as cool or not-cool, not your economic status. And some of my classes included kids with working class parents and kids from millionaire families.

Sure it's still not great, as if you can't afford to buy the cool clothes then you're being judged none-the-less - but I think it's a lot less bad to be judged as not cool than as "white trash", and at least in my situation it was possible to be understanding ("his parents don't have much money, so I'm not going to mock him for having cheap shoes").

I wonder which of our experiences is more common. I hope mine - but I have no idea.