It's more than the police. It's the school administrators and the governments.
After all, the police are tasked with enforcing the laws. While there are situations that police probably should just say "Fuck the Law" to, making that call is tough, and used wrongly can land them in trouble.
So while the police are partly to blame, they get put in a damned if you do, damned if you don't situation.
The same can't be said for those creating the regulations in the first place. And they also tend to be the ones calling the police out to enforce the stupidity.