Students who are late are given after-school detention, and if they miss that, Saturday detention. If they blow these off, then they are suspended. As a result, the halls are quiet during class, and students are on time. A teacher can begin teaching when the bell rings, and students get a full period of instruction, uninterrupted by stragglers. I do not think we do students any favors by allowing them to arrive at school or to class when they please.
Students are actually desirous of limitations on behavior.
There are norms for behavior wherever we go, and their enforement by authority is not necessarily oppressive. The key issue is the relationship of the institution to the aspirations of its inhabitants. If a teacher is enforcing rules arbitrarily, or in a way that attacks the integrity of the student, then, of course, this is oppressive. If the rules serve on the authority, and operate against the interests of the subjects, this is unacceptable. But if the teacher and school have as their goal the development of strong, capable students, and treat them with respect while setting limits, then the exercising of authority to establish and maintain a good learning environment is legitimate.