How about this: scan your state issued ID. My license has a barcode, and bars already scan it, so it’s a solved problem, no AI needed. The process should essentially be:

1. scan license
2. snap picture of face
3. send to police for lookup - needed to verify you’re not a felon or whatever, there’s more to it than just age verification
4. accept or reject transaction

The only AI that needs to exist would be at the local precinct, and used for related ID verification checks.