In a world where ubiquitous ID verification is required, you can just, like, mandate that stores with liquor licenses sell them. If they want to keep their licenses, that is.
A simple law against linking those two pieces of information would be sufficient. Sure, someone like the NSA wouldn't give two shits about what's legal, but they also wouldn't have the means to clandestinely get the necessary hardware installed in every one of the million stores that exist in the country.
> ...you can just, like, mandate that stores with liquor licenses sell them. If they want to keep their licenses, that is.
Given that the store makes zero money on the sales and faces Liquor Board-imposed penalties if they sell to an under-eighteen, I guarantee that the token-dispensing machines are going to be functional roughly as often as the frozen dessert machines at chain fast-food places.
Anyway. It looks like in order for your scheme to function, everyone (including lawmakers) has to play nice and both abide by the current rules and agree to never add any privacy-eroding ones for the rest of forever. Given that that's a precondition, here's a much simpler system that has been widely field-tested and has zero privacy concerns above what you get from simply using The Modern Web: