What benefits arise from uniforms? What's the actual cost of one missed class period? Or can offenders be sent to another class, like in-school suspension, where they miss no instruction, but they're not with their usual classmates?
I can tell you this - if there are no consequences for violation of rules, there will be no compliance with those rules.
Had an example of this earlier this year - brand new assistant principal (they're discipline in our school) who taught elementary for 3 years before becoming a high school AP. Student with a bad temper begins in August to regularly cuss and threaten teachers and classmates over items like being late to class, exploding with anger, shouting, screaming, walking out. This will continue all school year and escalate of course, into actually throwing desks, threatening death, hitting another student with an economics text in the head, using the phone to cheat on exams, and in general, creating fear and dread in all classes enrolled.
The AP "talked" to this student all year, never once suspending, assigning in school suspension, getting to a counselor, writing a ticket for truancy, requiring a parent meeting, nothing at all, just talking, because, he said, to all the teachers involved, he believed that behavior was improving and would improve more.
This senior student ends up failing every class and not graduating this spring. This outcome is on the AP's head - at no point did he insist that she act like all other students, complete her work, or even stay in class. She is not special ed, nor 504, nor a poverty student. She simply ran as far as authority would allow her. In her case, she'll have a 5th senior year, if she returns. This is what failing to enforce rules can do.
So are uniforms of value or not? I don't know - I have no experience with them. If none, chuck them. If so, enforcement will have to be done, keeping in mind that parents will also their kids out of school to babysit for little brother and sister so mom and dad can have an anniversary day to themselves, or for a dental appointment, or to travel to a league soccer tournament, so a single day missed is probably not a disaster.