I think all schoolchildren, public or private, at all levels, should wear school uniforms, address all their teachers as Mr/Ms/Dr Surname, and rise to their feet and and say "Good Morning/Afternoon Mr/Ms/Dr So-and-So" whenever a teacher enters the classroom, before sitting down again promptly.
I think this because there is a theory that all children, especially teenagers, WILL push and defy boundaries at times during their lives. If the boundaries are strict, arbitrary in a harmless way, and rigorously policed, going over the boundaries will be relatively harmless. You'll get teens loosening their ties, dying their hair an unnatrual shade, or wearing a ring on their finger. Those are safe and harmless assertions of individuality, and to keep it that way, teachers have to enforce students tightening their ties, re-dying their hair to a natural hair color, and removing rings from their fingers and dangly earrings from their ears, and keeping them off.
If the school rules allow students to wear anything they like, and to treat their teachers casually, asserting individuality at school and pushing boundaries requires secretly carrying dangerous items, and being disrespectful and disobedient to teachers, and general anti-social behavior.