Spotify doesn't pay much to artists because it doesn't take in much money. It has to remain competitive against piracy -- it can't charge $100 per month. I pay $10 per month to Spotify Premium and probably play 100 tracks per day -- whereas I used to pay $20 per CD that I'd probably play 100 tracks from in its lifetime.

The bottom line is that I pay a lot less for music now than I used to, and most people do, which means there's just less money from recordings in the pot that can go to artists.