Those of you who have read Fate is the Hunter by Ernest K. Gann will remember the chapter on a pilot who was engaged as a pilot on a new commercial airline in the immediate post war years without being asked to show his licence. Only after a display of spectacular ineptitude lead to an immediate flight check was it discovered that not only did he not have an ATPL (or equivalent) but did not even have an instrument rating.
IIRC, Gann later mentioned that this pilot had crashed, killing himself, his crew and passengers. Gann felt remorse for not 'outing' him.