The toilet thing. Children in secondary schools move about the school passing toilets on the way to each lesson, they get about 20 minutes break in the morning and then about two hours later get another 40 to 50 minute break. Are those are you telling me that there is not enough time provided or that your average 11-18 year old doesn't know at these regular intervals that they need to go to the loo? If there are exceptions likw someone asking irregularly to go to the loo most teachers will let them go. On very rare occasions a poor decision can be made but as all the teachers have said on here in the majority of cases the same few kids ask to go to the loo during each lesson, it's not because they need the loo, they just want out of the lesson for 5-10 minutes. The school also don't want kids wandering the corridor during lesson as it provides an opportuinty to misbehave and also if something were to happen during that time parents would ask: "Well why was he/she out of class? Isn't it the teachers responsibility for their safety?" We can't win!
Math, you asked why the policy was "subtle" make up. Well I'll repeat what I said earlier, you can either ban it totally which produces unsatisfactory results, or you don't have any rules regarding make up which leads to students coming to school with a full face of make up which has taken an age to put on. As we all know maintaining a full face of make up takes time, so during the day and can distract the girls from learning because they're re-applying their lippy in class, or taking 10 minutes in the bathrooms between each lesson touch it up. Again not ideal, so schools go for "subtle" which is a good compromise.
Many parents actually rely on school rules to help them with their teeangers and like them: "You can't pierce your lip becasuse the school won't allow you to be in class with it", "Get up now or you'll be late and the school will give you a detention" etc etc. Of course all of you on MN are perfect parents and your DC are perfect children who are mature and make balanced descisions but in the real world the school rules help parents to get their children to toe a line that they would like. Even the make up thing can be part of this, you can get your daughter out of the door on time because she isn't in the bathroom for an hour making sure she looks immaculate, or she actually remembers to pack all of the correct books for the day because she isn't making the make up a priority because you can only wear a minumum amount.
Again we go back to stakeholder interests. So yes the public perception of the school is important, sorry Math but it is, it has an effect on the number of parents that come to look round the school on open evening, if the public perception is not good people won't even bother. The more students on roll the more funding is recieved which means that the school can afford to do more, hire better teachers, the economies of scale achieved can result in more facilities and resources being provided, which in turn provides better educational outcomes. As stated above there are many reasons why parents want uniforms too and when consulted (I'm not sure about others but my school runs consultation sessions with parents regularly) parents overwhelmingly say that they want schools to have uniform and rules about appearance, so schools have uniforms and rules about appearance.
Also to the people saying teachers don't have to wear a uniform, the vast majority of schools have a dress code for staff which they uphold. In any case its a really good example of a Tu Quoque which is a flawed argument because it doesn't disprove the argument for any less credible. Same goes for cats argument regarding teachers knowing they can't leave the classroom and students not having a choice about attending school
To conclude (and go back to marking year 12 exam scripts) schools are trying to meet every stakeholder need effectively. This involves a level of compromise on many people's part. Uniform and appearance rules are overwhelmingly stated as a preference by parents so schools have unform and appearance rules, exceptions are made where neccesary, but the lack of compromise by posters on here shows that we can't make everybody happy. Until we have a societal change that means that uniform is no longer regarded in the same way the rules will stay, we have to try to change that, but attacking those who have to implement the current system as part of their job is rather futile and shows a massive disregard for people who are delivering an important public service.