It's really nothing - just a different fare code. Gate agents and cabin crew can already tell when someone is a non-rev (e.g. an employee using flight benefits), so looping them in on the backend is just a quick schedule lookup and a couple more people on the feedback system. (N.B.: I'm not saying this actually happens, because I don't know; just that it would be very little trouble using systems that are already in place. I, for one, didn't change out of my suit until after I'd gotten back home when I did an airline interview.)