This kind of restrictions expects account control to work. For example, parent's account & separate child account on a device. For the same reasons you describe, it will be ineffective: not tech-savvy. Children will use their parent's/grandma's account on TV and phone, one that has long been verified as "adult" despite the Youtube recommendations consisting of 6-13yo content.
If there were an organic push by parents, they would be happy to buy and promote products today, without waiting for legislation to catch up. Where are these local parental control products?
Speaking of social media and Youtubes of the world, why can't I, as account owner/parent, totally blacklist some "recommendations"?
Age verification is not a fit tool for content filtering. Users want the latter, but get switcheroo'd into the former.
You're assuming the politicians think this will be 100% successful and not, say, 80% successful.
I assume ulterior motives for politicians. It's their PR campaigns that do make it seem like it will solve all children's issues, if only we sacrifice a little privacy for their control. One thing that's never mentioned is increased vulnerability when (inevitably) personal data (of children) leaks.
I think politicians treat IDs as public info. Theirs are, and they have access to a lot of databases of all citizens.