Do you think the 15-30% is
only a "payment processing fee"? That seems an overly simplistic view. Apple is not asserting that it costs them 30% to run the transaction through a payment processor.
They're effectively charging for the entirety of the App Store and the development and maintenance of iOS and all the APIs that make it possible for developers to write apps in the first place. They built an ecosystem, and it costs money to develop and maintain, plus they're entitled to some profit. They could, instead, say, charge every develop $1 million a year, up front, to use the libraries, APIs and ecosystem, but that would be so burdensome to small developers as to chase most of them out, while it might not be enough for a few really large developers. Better to find some way to charge for everything Apple is offering/providing to developers in some more equitable manner. So, first pass, "develop your apps and put them in the store at whatever price you want and we'll take a 30% cut". This, frankly, roughly matches what a whole lot of other businesses do. And apps that sell a lot, pay more, and apps that don't sell much (or are "sold" for free) pay very little or even nothing. This seems pretty fair. Then... then developers and users wanted IAPs. And some started charging less for the initial download, making it up on the IAPs (and "free to play" games were born, sigh). Now, if Apple didn't charge for IAPs equally with initial purchases, then developers would have made pretty much every single app in the store "free to 'purchase' with IAPs to unlock", and Apple's funding model for all of this would have collapsed. So, everything gets charged the same - initial purchases, IAPs, everything.
Now, people are saying, "hey, wait, I can get a credit card transaction processed for way less than 30%, so let me do it myself (and then don't charge me
anything, right?)". Except they're making that mistake of thinking the 30% is a credit card transaction fee. It's not. Take the banking fees (3-4% has been bandied about) out of the equation and you're still left with the rest.
I don't know what to do about, say, Apple Music vs. Spotify. Perhaps the answer would be to spin Apple Music out as a "separate-ish" entity that has to pay the same fees as everybody else, in order to level the playing field. I'm not sure that would fix the situation.
(Personally, I wish all-you-can-eat subscription music streaming had never become a thing - it pays vanishingly little to the artists. Or, if they were going to exist, they should be much more costly. As it is, the companies are essentially saying, "well, this person streamed these thousand songs this month, and they paid us $10, so after taking out our cut and the record label's cut, we'll give the artist half a cent for that song". Rather than a smaller number of people deciding to actually buy the song. It's not a good deal for most artists. Rather than starting from what would be reasonable to pay the artists and working out what to charge for the service, they started from what they wanted to charge for the service and worked backwards from that to figure out how much to pay the artists. From
this article -
a random Google hit, it looks like Apple Music pays about 0.78 of a cent per stream, while Spotify pays about 0.44 of a cent per stream - to be clear, the
larger of those is about 3/4 of a penny.)