Plus, you'd be giving Google your government ID. A company that collects and trades thousands of your behavioral metrics as their core business model.

The Baltics have handled this better with a Smart ID system[0] that also allows cryptographic document signing (like Adobe Sign but non-repudiable by law). It can perform proof-of-human like Altman's orbs, and allows Baltic citizens to file documents with the government, access electronic court records, electronic medical records, e-banking, and similar services.

One downside of the system is that its purpose is to identify a natural person using a service. So whichever service uses it as authentication, it will receive personal data. However, there are third-party sign-on gateways that use Smart ID (and other e-signature methods legal in the Baltics) to authenticate users and only disclose certain bits of personal information to those requesting authentication. In Lithuania, the government operates a service called the E-Government Gateway, and one can easily imagine it could be used for zero-knowledge age verification.

Ultimately, Google seems to be offering a far inferior product at a lot more risk to the user. Once again, their core business is user profiling, associating various user metrics with each profile. A government ID is the holy grail for user profiling. It's sort of like if a wolf offered a sheep-verification service - yes, we could trust the wolf to act professionally towards the sheep, despite it coming out in sheep court several times that it hasn't in the past. But is it wise to suspend disbelief like that? It's better to leave this to independent, expert companies, or even governments.

[0] https://www.smart-id.com/