I don't understand why you see these as either-or propositions. It's important that I parent my children to understand the dangers of alcohol, and it's also a good idea that it's illegal for my local grocery store to sell them any, and neither of these are contradicted by the fact that they'll be able to find some if they really want to. Norms and friction matter.

It’s a good idea for grocery stores to not sell children alchohol. It’s a bad idea for grocery stores to not sell alcohol to ANYONE, adults included, because children might buy it by faking their IDs. That’s the difference here.

Alcohol is a perfect example as well, because I personally drink it only occasionally but would very much rather see it completely banned, as I think it would solve a lot of problems with society. In reality it likely wouldn’t, but the gut feeling is there. If I were to blindly follow my instinct and not know history, I would call for a total ban on it to protect the children.

The same is happening here, but at a much more dangerous level.

Plenty of friction exists. Access to devices being banned at schools, ISP parental controls, selective DNS blocking, Google/Apple child accounts. For the most part it's just carelessness. Before the Internet children that were persistent enough and that had apathetic parents still found a way (perhaps less volumes and less extreme though)

> it's also a good idea that it's illegal for my local grocery store to sell them any

As someone who has been a kid, I would call such restrictions "performative" rather than a "good idea".