Social engineering, the second oldest profession
Making phone calls, convincing people to bypass the mechanical security...
Have we become so focussed on the clever coding and machine based security that we've been forgetting to train everyone to look out for the old tricks? Human Factors Engineering, if you will.
(Ok, some of it is just good old fashioned laxity - not using your TFA - which is just the back-end Human Factors kicking in)