I feel like a question about OS-level age tracking that would've been obvious to me, were I not a tech person, is: what about shared accounts? I'm not just talking about library computers. Tech people will create a separate account for everyone who uses a device, but I think most people set up one account with no password and never think about it again. If you try to force them to set a password, they will sticky-note it to the screen. How is this going to work in practice?
Fantasy: This won't work because there are all sorts of technical work-arounds and corner cases that it doesn't account for, that us tech people can imagine. Kids will pass around USB boot drives and use them to
Reality: This won't work because NOBODY CARES.