They do, whether paying for an App or having to watch an Ad, everything is paid in some way or another as a result of users. The user is king.
Exactly the way it should be. The user is king.
Developers set whatever price they want for their app, the user decides whether to pay that for it, if the app developer hasn't factored app store fees into the app price then that is their mistake, not the users.
The whole 15%/30% is never the whole story, people just like to focus on the drama elements.
How much of that will the app developer have had to pay regardless had they not had the app store?
Easily 15% of the app cost will translate into merchant fees, fraud, chargeback costs, time to administer and so on.
Then Apple is providing the tools to develop the app across their entire range of devices, widening the reach of your app, then direct and immediate access to the audience of 1.5bn+ users and the management of app delivery and the list goes on. Worth the remaining 15%? I think so.
Dry your eyes developers, either suck it up or leave the platform and develop elsewhere, better still, go it alone, see how long you last.