While I agree with your claim that it is likely the number of third parties info is being routed to is likely related to per-query economics, I want to note that ZKP are not magic. They tend to either be worthless at preventing fraud or require so much additional context as to question how much privacy is really being preserved.

While ZKP is more useful in limiting how much info is provided and, depending on implementation letting you make sure of the full scope of information acquired....if it literally only validates age then there's nothing other than logistics preventing a single adult from authenticating the entire world.

Totally agree. Was just trying to emphasize that there are better ways to do this if privacy and security are something that Yoti actually cares about. ZKP is not a magic bullet.