I could support a law/regulation that requires Class IV ballistic shields and plate carriers with plates be stored and properly secured/maintained at all school facilities.
Given my school has a 190 million dollar budget, I'm sure they could build a storage facility on the school and maintain all the gear they would need to outfit police in seconds. Plus have all the entry passes/fobs, battering rams, etc.
But then you’d have whiners crying they lost the key so couldn’t get into the storage room or the room was too close to the shooter. It’d also waste another hour or two deciding how to get to the room while more babies are being killed.