They didn't do it because it's reasonable. They did it to send a message. Ain't no different than the health inspector or building commissioner acting way too big for their britches knowing full well there will be no consequences.

Look at public schools as just another municipal enforcement department tasked with making sure the kids all meet state standards and it makes sense (or at least to the same extent that all the other indefensible shit done in the name of government makes sense).