> I know exactly the criteria google uses to show the ad to someone, because that's what I buy when I buy keywords. No, you know exactly the criteria Google re

> I know exactly the criteria google uses to show the ad to someone, because that's what I buy when I buy keywords. No, you know exactly the criteria Google requests from you when you buy the ad. That's most likely a subset of the criteria Google uses to display the ad (which can include things like the past performance of your ads / of similar ads, in different contexts, for different kinds of users and probably all sorts of stuff I'm not thinking of).