Age-gating
I'm not opposed to age-gating at all, I think it's appropriate in many situations and useful, and democratic societies can decide their own rules there. But it should be handled and authenticated as low-level as possible, at the operating system layer. See also: Australia's Senate bans social media for kids under 16. But there are lots of other less controversial examples, like adult websites, or ordering alcohol online or through an app.
@photomatt FWIW, in the US, we can't even keep kids and crazy people from getting military-grade weapons, so I'm suspicious of anything that says "let's start enforcing ID checks for social media".
I was a 16yo kid once. I know what happens when you tell them they can't do something.
Crazy idea - require the advertising-surveillance industry to report identities they suspect to be underage, trying to do underage-things. They track it, profit from it, model it. Make them share it, like a tax.