I will agree that the need for blazers and some of the 'branded' uniform items are a bit OTT (in my opinion) but that's the uniform policy.
However, if the uniform policy is clear then the children should wear the correct uniform and wear it correctly.
If homework is given then it should be handed in on time.
If sports kit, textbooks and stationary are required then it is up to the children (with the support of the parents) to ensure it is taken to school.
If the rule is 'no water bottles during lessons' (and, having spoken to teachers, there's very good reasons why this rule exists) then don't have a water bottle out during lessons.
None of these things are difficult. None of them infringe on human rights. Overlooking rules and standards (even if you don't agree with them) shows a lack of leadership and authority which, given teachers deal with hundreds of kids/teenagers, is essential in maintaining a productive environment for education.
I don't always agree with some of the school rules and, if I feel strongly enough, I may feed this back to the school. HOWEVER (and this is my main point), parents and teachers need to provide a united front when it comes to following rules and expectations.
The idea of telling your children 'this is a silly rule so don't worry about it' completely undermines the whole schooling process (and it's this attitude which has probably led to stricter rules and harsher policing of said rules being required)