It's not about efficiency, it's about avoiding getting caught for criminal acts. Since criminals don't pay taxes on their earnings and don't have to pay for all sorts of things others do, they're already more "efficient"
Sure, but if you're going through a distribution service that has a 60/40 split with Spotify, are you going to be okay with 40% of your laundered proceeds getting eaten by Spotify? How does that compare to other laundering opportunities? And that's not even counting the costs imposed by your distributer. For example, if you have 1,000 tracks, on TuneCore that's $10,000 dollars just for track distribution, as well as a $50 per-album yearly fee. It does seem somewhat inefficient, and very easy for Spotify to notice and crack down on. (But they don't have a lot of incentive to look too closely, since they're getting paid handsomely for it...)
