Forgive me if this has been said before, but it seems that a lot of the problem with school rules these days (perhaps all rules) is centralized decision. Instead of letting teachers set rules, or just decide on a case-by-case, the whole school, or the whole district, or the whole state, or the whole country, has to be on the same page. Cuz if'n we're all micro-managed in exactly the same way, everything will be fair, and no one higher up the food chain will ever be criticized for someone beneath them exercising independent thought.
Foolish consistency, across all degrees of separation, breeds hobgoblins for the rule-happy bureaucrat or the over-zealous libertarian.*
*Sorry about that. In my tiny mind, I'm still mulling over some forum member's critique of federalism, local zoning laws, vote-with-your-feet, etc.