The only—I repeat only—reason the labels allow competing stores to have DRM-free tracks is that it’s the only way to get music onto an iPod. Think about that for a moment: Apple’s dominance of the music player business is the actual reason you can buy a DRM-free track from Amazon. If anybody else had a substantial chunk of the player market, the labels would be busy trying to make the other player’s DRM the standard.

Why Apple is More Expensive than Amazon