MaisyPops maybe my dislike of the uniform rules is a wider thing based on my dislike of much to do with schools. This is based on my own shite experience of school and my daughter's primary and middle school experiences. (My son's primary experience has been very good and my dd so far has had mostly good experience of secondary.)
Sadly, those of us who had bad experiences of school are very much affected by them and maybe they colour my thinking on these issues.
In all these schools that are represented here, on Mumsnet, and in the UK anywhere, there will be children struggling with a vast array of issues and concerns, problems, struggles. The amount of time and energy put into making children wear school clothes. These clothes generally (ties, most will not go on to wear ties, blazers - totally impractical, hot in hot weather and not done up so not really suitable for bad weather), are not conducive to education. So to me a massive waste of time and effort. I wold like that time and effort, that energy, to go into things of real value.
One school I visited on a hot day had children in blazers while the teacher taught in shirt sleeves (rolled up, I think), how is that conducive to learning? (We did not send our child there.)
Maybe schools can be wonderful places, I am sure. I just have the kind of feeling about schools that some people have about hospitals (conversely, ironically, I like hospitals!). So because I see schools as places where problems happen, and things can be very negative. I resent the amount of time 'wasted' on discussion on clothing.
And the idea that a school would see a parent not wanting to 'waste' £50 on new school shoes, when existing good shoes were available, as somehow being rebellious - that makes me frustrated.
I would expect parents to back school up in many areas but the uniform is vanity, to me.
So I don't expect you to understand my reasoning, but I am trying to explain why this is so significant to me, because clothes to me are so insignificant, and a school that places a high emphasis on shoes and would comprise a child's education over this is really setting a terrible, terrible example to children IMHO.