I have to admit I don't understand this, all those numbers are completely arbitrary and seem to be based on what you think is right and not on any economic data

I have to admit I don't understand this, all those numbers are completely arbitrary and seem to be based on what you think is right and not on any economic data. It seems to me the real question is whether the Apple App Store should be regulated or not. If it reaches the legal threshold to be regulated, then either they should open up to competition and let the market do the price discovery or be regulated like a utility and have the price set for them. If they don't reach the threshold, then they should be free to set whatever price they want, and you're free to go elsewhere if you don't like it. Of course, the big question is whether the app store reaches that threshold, but I'm not sure whether they charge 30% or 20 changes anything.