Your first link was about a call made by a Quebec based show. The second was made by an online newspaper. Neither of which are under the FCC. If either were made by American radio shows they could have been fined.
The early Rush callers were certainly all fake.
My understanding is that it is still legal to play recordings of calls made to other radio stations and tv stations. Obviously, people broadcasting have no expectation of privacy. It would be no different than playing a clip of the other show on the air. A prank caller recording would be no different than recording a legit caller.
Yes, call-in radio shows are explicitly legal by that FAA code. If you are calling in, you have no expectation of not being recorded. Ergo, the one calling in also recording should be covered. But the recordings are probably from the show itself.