Really? Tell me, what right do public (i.e. government) schools have to tell parents (i.e. taxpayers i.e. their BOSSES)how to dress their children? What right would a county bureaucrat have to knock on your door and tell you what to wear? It is the same thing. Parents will judge what is appropriate for their children and public schools have no right to say different.
They may not have the 'right'; but they damn sure have the POWER!
Have you met some of today’s parents? They have no more clue about appropriate attire for school than a goat does.
Parents should give common sense input into school dress codes and speak up if the code is just plain impractical. For example forbidding short sleeved shirts. But yeah schools, any school have the right to establish codes of conduct which includes how a student may dress while on campus, provided such code does not violate a student’s right.