I work at a European identity wallet system that uses a zero knowledge proof age identification system. It derives an age attribute such as "over 18" from a passport or ID, without disclosing any other information such as the date of birth. As long as you trust the government that gave out the ID, you can trust the attribute, and anonymously verify somebodies age. I think there are many pros and cons to be said about…
The average person does not understand the math behind zero-knowledge proofs. They only see that state infrastructure is gatekeeping their web access. Furthermore, if the wallet relies on a centralized server for live revocation checks, the identity provider might still be able to log those authentication requests, effectively breaking anonymity at the state level.
On a practical level, this method verifies the presence of an authorized device rather than the actual human looking at the screen. Unless the wallet demands a live biometric scan for every single age check, they will simply bypass the system using a shared family computer or a parent's unlocked phone. We used to find our way around any sort of nanny software (remember net nanny)
what you are describing still remains a bubble and I really hope Americans aren't looking at EU for any sort of public policy directions here.