Some thoughts:
1) When you purchase a song or album (download, CD, vinyl) you're paying/licensing for all possible future listens #Spotify #AppleMusic
— Mike Shupp (@MikeShupp) June 11, 2015
2) When you stream a song, you're paying/licensing for one (1) listen #Spotify #AppleMusic
— Mike Shupp (@MikeShupp) June 11, 2015
In other words,
The purchase of a song or album (download, CD, vinyl) secures the licenses from the rights holders for you to listen to that song, or album, whenever you want, wherever you want, as many times as you want, for the rest of your life… and the royalties due those rights holders reflect those uses.
But a stream of a song needs only to secure licenses from the rights holders for one (1) listen by one listener… and the royalties due those rights holders for that stream reflect that use.