I used to be in favour of uniform but I'm not now.
Rules for health and safety eg long hair tied up, shoes that cover toes and aren't a fall hazard (high heels) but don't agree it stops one upmanship or cost issues.
Either the school is super strict, everyone has to wear exactly the same and this can only be achieved by only having one shop sell it and they charge a fortune
Or school not so strict and so you get some kids wearing supermarket uniform and others wearing from high end shops and the kids definitely know the difference and that causes issues.
Most other countries don't have uniform (only ones I can think of are Australia, China and Japan) and yet still have students that do well in school and go to uni and have professional careers, the ones that do have uniform still have kids that don't do well in school and go off the rails so the argument that it improves concentration and limits distraction in school doesn't work either.
I attended 2 high schools (military brat) the first had a relaxed policy was a great school with good teachers that got good results.
The second had a strict policy (detentions for wearing wrong colour hair bobbles) but had an appalling educational record. Frankly the head cared more about image than employing decent teachers and educational attainment.