To enforce restrictions is indeed very hard. I know because I do it, using a whitelisting proxy. It's possible (even uncircumventably for mobile devices, using a managed device and an always-on wireguard vpn) but it is far from trivial to do and I am in a vanishingly tiny minority in doing it.

To enforce literacy is of course easy. Talk to them, teach them.

To enforce that a child actually follows your advice not to watch thing X when they have the physical ability to watch thing X, including when you aren't looking? Basically impossible. Kids aren't computers. They don't necessarily do what you tell them to do.

I mean, I have massive difficulty getting myself not to waste my life on the internet, this very comment being evidence of the fact.