I don't want them to use it. I agree with all your points.
I strongly disagree that mandatory ID on the net is the solution to this.
It also fascinates me that you'd think putting such a tool, with all the trouble it could cause if our countries stop being democracies, in the hands of government as a purported solution to children being on social media. That's throwing out the baby with the bathwater
There are other ways to ban social media for minors that don't go through full fledged online IDs for everything. But you seem to want to ignore that, it's a false dichotomy.
Banning social media for minors (or better yet, opaque algorithmic feeds for everyone) = Good.
Trying to achieve that by giving overreaching powers to a government, that can be used as a tool of oppression when democracy wavers = very bad.
As for low trust societies, mate, I've been gassed, beaten up and shot at with rubber bullets by riot police in Spain, for the egregy crime of peacefully protesting. It's a country where the memory of the dictatorship, and it's power structures, are still very much alive. Francoism never fully left