I strongly doubt that "most people" think that Amazon pays 20% of the asking price to the dev. Maybe if you limited your audience to "Android developers very interested in the Amazon App Store", but that's really a pretty limited audience, and not who your app is targeted to. Has Amazon ever trumpeted that 20% figure to the public? No. I mean, I work for a competitor, and am ready and quite willing to see the flaws in their model, that's a horrible thing to compete against, but it absolutely does not surprise me that they're not giving away their money. I mean: it's clearly not necessary. Once they run out of indie devs willing to give their app away for nothing other than incredibly great exposure, then maybe they'll need to start paying out, but not before.