The question is whether radio stations provide a service to artists by promoting their wares on the air, or whether they are exploiting them. Seeing (or rather listening) that radio stations rarely mention who the artist is, the latter would seem to hold. But given that artists often give songs to stations for them to be played, one would argue the opposite. And if the station actually buys the CD, wouldn't it be allowed to play it like a library allows patrons to read its books?