I use Apple Pay quite a lot and I'm looking forward to vaccination record support in iOS 15. But I don't think I have a use case for this. If I did, it would be my choice; I don't particularly like do not need to unlock, show, or hand over their device to present their ID.
Still I'm ok with Apple providing this feature, but I have to find a use case before I'd use it. And I don't like its opt-in once, broadcast thereafter approach.