I'm not quite sure what you're getting at here.

The Google system is tied to a mobile driver's license, and there is an identity check at enrollment that is intended to tie the credential to the device. It's true that if you give someone access to your phone without erasing it, then they can potentially use this mechanism to circumvent age assurance. This is true for a number of other age assurance mechanisms (e.g., credit card-based validation).

In any case, I'm not really interested in getting into an argument with you about the level of assurance provided by this system and whether it's "trivial to abuse" or not. I was merely describing the way the system worked in case people were interested.