Right, I take it the screeners themselves aren't human then?
Or wait, do they have "clearance"....So can/do many pilot's lets not forget. If we followed this principle we'd be screening each other for weapons and other sorts of dodgy goods. Show me yours and I'll show you mine (or not as may be the case). We all know terrorists wouldn't go through screening if they had something to hide. So Excessive screening is just becoming an act useful to those who wish to control (get used to it citizen!)