FYI for adult content, there's a standard called RTA-Label that already integrates with all parental controls and is already deployed on all major adult sites.
RTA is an excellent demonstration that a self categorization system can be expected to work provided it's standardized and service operators make use of it. What's missing then is granularity and a way to coerce the vast majority of sites to adopt whatever gets standardized.
Given the current browser duopoly coercing adoption should prove relatively straightforward. So we just need an RFC document and then to somehow gain public support for it.
Recall that this is exactly what happened with TLS. When browsers started gating all new features behind TLS being active suddenly all the mainstream sites had it working across the board in record time.
The first step is to get Google and Apple to set a date after which adoption is mandated. Provide an easy out for site operators, such as placing a text file at "/.well-known/content-rating" with "tag:all ages" inside to opt the entire site out rather than sending a header per resource or tagging html elements or whatever.
The second step is to approach legislators with this standard and a now very high compliance rate in hand and suggest that they enact a law requiring that such ratings are accurate for certain specific categories (presumably porn, gambling, social media, and user generated content).
The third step is getting governments to do spot enforcement often enough to prevent the system from falling apart.
Keep in mind that for a long time online retailers in the US weren't even collecting sales tax properly and then for a while there was disagreement about which state the sales tax should go to. It seems like a computer and the network enter the mix and suddenly the IQ of everyone involved mysteriously drops to room temperature.
My impression is that the latest push involves parents wanting to do "something" but not being sure what that "something" ought to be. The legislators in turn are either in league with lobbyists who have a vested interest in online ID for one reason or another or alternatively they merely feel similarly to the parents that "something" ought to be done but they don't really have any good options. It's unfortunate but I don't think it's realistic to expect legislators to go out and have a usable web standard drawn up when one doesn't already exist.
Because that is the only acceptable solution and it doesn't violate user privacy. Other than off-by-default parental controls that are optionally enabled.
> Because that is the only acceptable solution
And this is how you get locked down computing