The main advantage of school uniforms is that they prevent children realising that some parents are better off than others.
They may also teach children that work clothes are necessarily different from what you wear at home, or when going out, but I doubt this. The school uniforms I wore were so hideous that we could not wait to leave school and not have to wear them.
But as an adult, and a teacher, in a country that does not have school uniforms, I have often felt that it would be a good thing to have them, rather than the fashion parade that children's school clothes become when there are no uniforms.
I haved taught girls in crop tops, boys with their trousers so far down their backsides that we could, pupils and teachers alike ,see the colour of their boxer shorts, mini-skirted girls whom women staff had to pull aside and tell to close their legs when sitting down, and 16 + girls in scoop necklines that left as little to the imagination as the lads' tight trousers that clearly showed us all which side they dressed!
Some standards do need to be maintained, but if uniforms are to be used, they should be cheap, washable and not impoverish parents who are not well-to-do.