Zk would perfect for online age verification, but governments do not want to implement it like this. Instead they want id and face collection for mass surveillance, using age verification as an excuse.
One problem with private age verification is that because each verification cannot be traced back to a user, it is hard to prevent abuse like credential sharing. Imagine how a single stolen credential can be used by any number of users because the verification step kept the credential private.
Google is rolling out ZKP for age verification with state-issued digital IDs. See https://www.eff.org/deeplinks/2025/07/zero-knowledge-proofs-... for context
Based on recent revelations with certain "files" and brazen disregard for human life, I find it hard to believe that the "people" in the gov really care about children at all.
For age verification and identity verification both afaik. Sometimes I wonder if what's needed is "just" a more public push for it, but these topics are so hopelessly technical, I think it has no hope to ever reach the mainstream and poll well. And that is ignoring all the other counterarguments against these that compound on top, some of which are culturally sensitive for many.
Europe is rolling out ZKP afaik.
The actual problem with ZKP is that you need a way to prevent generating thousands or millions of assertions from one ID and distributing them to whoever wants one, in a way which is undetectable and unstoppable by the government, and the only way to do that is with Google Play Integrity Protection and such.