School uniform is a way of saying you belong to the school and the rules apply to you for wearing it.It shows the dominance of the teachers and separates them of power. It helps keep students as one and in line to follow the teachers orders and is good to keep them enforced to look smart as it shows who's in charge. It also shows the authority and let's the students to be more visible. Having a constant rule of tucking in a shirt and fasting your top button etc helps discipline.