Parents don’t have access to every device children have access to either

Either parents or the school... and if the school doesn't have a pretty significantly locked down network, that's a separate problem.

Also, you're right, I misspoke. While some of the bigger websites have decent-ish parental controls, I was more thinking of device specific parental controls. The amount you can lock-down (and monitor) a phone you give your 12 year old is pretty impressive. I'd rather parents did that than hand the monitoring, censoring, and access over to various government agencies all over the world.