Perhaps you overestimate the power of proofs of knowledge. These can attestate that you know something in a mathematical sense, and that's about it. So far we don't have such a connection to physical objects.

For instance, a proof of running a text recognition program can't differentiate between genuine and edited photos. Well, some belive that if photocameras outputted proofs alongside images, the situation would change.

Anyways, I have a few words regarding zero-knowledge applications in the context of cryptocurrencies.