[j2kun]

> How would you prove to the black box ZKP that you are the phone owner?

My point was that your described flow was just shifting the burden of identity verification from one service to another. I think the ZKP solution has the benefit of the government not having to coordinate with other services. They can ship one set of cryptographic material to your device (with a single time when you have to do your annoying passport scan) and then you can do age verification with any service indefinitely. Heck, with a range query you can get that material when you're 16 and you're issued an ID and use it for age verification checks at 16, 18, 21, 25, whatever. I think there's a lot to be said for flexibility of the application here.