WIY, you go to work to earn money, honestly. As long as the rules are legal, you don’t have to agree with them. OTOH, when we choose to send our children to a school, we are entering into a partnership in being mechanech our children. It is clear that schools will often have stricter rules than the house does. Many BYs will limit the makeup girls are allowed to wear in school, not necessarily because they feel there’s something wrong with a 17 year old girl wearing even a subtle color of nail polish, but because it is too distracting and disturbing to force the girls to show their hands everyday, or otherwise start policing.
Without going into particular feelings of the situation that seems to be a springboard for this discussion, I just wanted to point out that one can’t so quickly extrapolate from the work place to school, or vice versa.