Why do american schools seem to have a problem with long hair?

OMG that is just wrong! I mean, your hair is YOUR hair... It is only hair, and nothing more. It is on YOUR head and body, not the schools, not the teachers, and not even the lunch ladies. I don't even understand why American schools care so much about it... EVERYONE has hair (or had it when they were younger...) and no one should start another ongoing dispute. We already have enough of those, and HAIR should definitely NOT be one of them... Everyone needs to realize that and move on. Hair is a part of you, and you cannot change that. Maybe we should all go bald, and see what happens when we go to school. They would probably accuse you of having too LITTLE of hair, or no, starting a RIOT and bringing DRUGS to SCHOOL... It makes NO SENSE...