IIRC there wasn’t anything about the OS needing to validate the info, just ask for it at setup and provide it when requested. Part of me wonders if this was just an attempt to stake out a position as to what a law of this sort, that still respects privacy, might look like.
I dunno. I don’t love it. But if a dumb age-range flag became “the thing” to check, well, that’s be less invasive than uploading an ID or something.
If you actually read this law, it does exactly the opposite to avoid every random app/website from having to do age verification (like traditional age verification laws requires). It requires that only the OS to ask the user's age (not even verify it). Individual apps should use the age buckets signaled by the OS.
California is kind of strange - on the one hand giving rise to open source; on the other hand being a lobbyist's paradise.