alt Hacker News> A ZKP will work as a base, but the proof mechanism will have to be combined with anti-user measures like device attestation to prevent things like me offering an API to continually sign requests for strangers
Spot on! The "technical" proposal from Google of a ZKP system is best seen as technically-disingenuous marketing meant to encourage governments to mandate the use of Google's locked down devices and user-hostile ecosystem.
The only sane way to implement this is to confine the locked-down computing blast radius to the specific devices that need child protection, rather than forcing the restrictions onto everyone.
I'm not sure what I feel about depriving teens of general purpose computing devices, either, which is the logical consequence of both the pseudo-ZKP scheme and parent's "underage signal". I believe most of us here learned programming through being able to run arbitrary programs, and that would never have happened if we only had access to locked down devices. And that habit of viewing computers as appliances controlled by other people isn't going to go away on their 18th birthday either.
Overall I think while there is a reasonable argument in favor of age verification for some types of sites, the harms of implementing it would drastically outweigh any benefits that it should not be done.