The law as I understand it was that it was illegal for money to change hands and the radio station not know about it. It was only illegal for program directors and DJ's to take money (and for the radio station to not mention that they were being paid to play songs.)
|And then at some point somebody invented the Internet and I started posting pictures of pigs.|
But then I guessed that this happened. When big conglomerates took over radio stations they realized that the payola they could get was nothing compared to advertising time. Because 30-second spots on a top-rated station in a big market.
And here in this Cracked article they even point out that Limp Bizkit's record company only paid $5,000 for 50 plays over 5 weeks. That seems like some pretty cheap advertising to me. Yes, it was in a secondary/tertiary market but still...
There are, surprisingly, a number of advocates of payola. Read all about them in the New York Times. I recall that in Hit Men there were indy labels which were reliant on payola and which died out when payola died out.