The general takeaway is that you can prove you know something without revealing what it is, or how you know!
If you can't think of the possibilities that unlocks beyond the examples others have already discussed(none of which were crypto related), that's a limitation on your end.
And you still have to do that with ZKPs. Otherwise, I can just "borrow" my buddy's license and get into a pub. Unless the ZKP will interface with a biometric authentication system and do something like facial recognition.
And even then, it hand-waves away the issues with revoked licenses. How do you do license revocation with ZKPs?
