From the Age Verification Blueprint:
AVI [Age Verification App Instances] SHOULD support the generation of Zero-Knowledge Proofs
Maybe I'm not seeing the full picture but as long there is a 'should', the whole thing is worthless. Keep in mind, national states need no implement their own solutions and AFAIK during the pilot phase ZKP was just skipped. Could be for other reasons (was not finished yet) but in the end a 'should' is a 'should' and no 'must'.
Source: https://ageverification.dev/av-doc-technical-specification/d...