I can only guess it has something to do with a 'package' of songs they license for a set fee. More songs would cost them more....?
actually its the other way around. record labels pay most radio stations via intermediaries ("indies") or directly in order to get songs played. which is probably exactly the answer to the original question asked in the thread. of course, radio stations can license music to play it - but why do that when they can cash out big time and all they have to do is play the newest single off the hot new record? over and over and over...
