I think y'all are over-thinking this. The reason for less invasive pat-downs could also be as simple as most individuals do not particularly enjoy touching the genitals of people they are not sexually attracted to. Speaking as a reformed federal flunky myself, government workers (excepting the few true zealots) try not to let their work put them out. So when you simplify it, everything makes sense: an employee who may have barely finished high school and was recruited off of a pizza box is going to take little shortcuts when they can. Occam's Razor in action.