Actually a lot of white label releases do pay some money back to the artist, usually when it is pressed because of copyright violations. The rest are usually pressed to be distributed to djs prior to an actual release of the song. They know these "promos" are going to end up in the record bins of stores and they don't mind because it usually means even more djs will play the cut. You notice I use the word usually a lot because it's not all that UNusual for these discs to be complete rip-offs.