Some (popular) radio stations are paid to play songs. Someone must have realized that exposure is value gained, not lost..
5,000 plays on Spotify or Pandora is not equal to a single play on terrestrial radio. A single play on terrestrial radio probably reaches closer to 10,000 listeners, depending on how large the market is. In other words, 5,000 plays on Spotify is less than a single play on terrestrial radio.