Fair enough, but the topic was whether Apple was charging too much. Are you suggesting that if Apple opened up their platform to additional app stores or allowed sideloading, the 15% or 30% would be fair?
Stores can then actually compete on merit.
See that's the thing about actual competition is a price can be determined by the market, especially in the case that you have many players rather than a duopoly. In my case Apple could charge whatever they wanted, 30%, fine. But me the app maker could go to the A+ store and pay 10% instead.