It takes 5 seconds to come up with the answer. Don't worry about the machine - just make sure the guy operating it is one of yours. Then he'll wave your suicide bombers through - underpants and all
One would hope that the shift patterns would take that into account, and not make it predictable who is scanning and supervising at any one gate.
Of course, one would also hope that the people are awake on the job and that the security cameras work, but
here's a case where neither happened. Oh look, and it's not the EU's fault either.