I just had another thought.
If people want rules on school uniforms, let's have them. On a national level. Managed by the Department for Education.
We could start with something simple, like banning schools from rip-off single supplier deals. No longer uniform 'should' be affordable and'should' be available from a range of high street retailers - no, those become 'must'. Let's have maximum pricing for items of school clothing if schools want to go the single supplier route. Oh, so suppliers will go out of business? Well boo-fucking-hoo, they have been ripping families off for decades.
And sports kit? Let's do away with the fancy 'separate kit for every single sport' nonsense. Simple basic kit only, a set which will cover all sports, again subject to price limits.
Logos? Must either be part of the above mentioned reasonably priced kit, or must be supplied at cost as iron-on and/or sew on badges.
Hair bands, socks and other nonsense? Not allowed. If a student fiddles with hair bands, they get done for being disruptive. But no detentions for 'the wrong hair bands'.
So everyone will be wearing state mandated uniform. Nice and easy, no need for endless uniform policing at schools because the rules will be the same everywhere. Think schools, especially the kind of academies that pull this petty uniform nonsense, will like this? Of course not. Tough. If you're going to have an obsession with uniform, let's make it a national one.