pointy why do scouts have a uniform? It’s not just about cosmetic conformity is it? Sense of identity and so on. Schools in the US don’t have uniform but some create a school identity (as far as I can tell from watching TV) involving sports, mascots, cheerleaders and the like.
There are also behaviour management reasons. If I can stand at the threshold to my classroom and not allow students in until their shirts are tucked in and their ties are on properly, then that’s a useful tool. Kids will test school boundaries, uniform gives them an easy and harmless one to kick against.
And there’s the equaliser argument.
There have been lots of uniform threads in the past. But in general, just because the UK do it differently, it doesn’t mean that they are doing it badly. And just because you can’t see a reason for something, that doesn’t mean there isn’t a reason for it.
Blazers should be off in summer though.