It was the talk of the town back in the late 60s at the former Eastern Airlines [USA] where one B727 pilot apparently had "fallen through the cracks" with only a private pilot's certificate.
As to new pilots coming into the right seat of a big jet; the experience level becomes immediately apparent, no matter how many hours one claims to have actually flown . . . or logged on paper. Pilots' experience levels can usually be measured during initial sim sessions.