Amazon pays Apple $100/year to host the Kindle app, and only the app. All of the books that someone may buy sit on Amazons servers that they host and distribute. Amazon also manages its own payment infrastructure and everything else that deals with getting a book into the Kindle app. Both companies benefit from having the Kindle app in the app store. Apple gets to brag about how many apps are for sale for iOS devices (thus sell more devices), and Amazon gets to sell books.
We could always look at it from Amazons POV. They are providing the content that makes iOS devices more desirable for consumers. Why isn't Apple giving them a cut of each device sold?
It will get hard for me to keep playing this game because, as I suggested, I disagree with Apple here. However, it's a fun exercise.
Say that you go to a grocery store and reach an agreement: you'll be selling apples, you'll pay $100 in rent plus a 30% cut. When you actually begin working, you don't "sell" any apples there at all: you just show people how to order apples for delivery and giving them an apple bin for the truck to unload into.
If the grocer argues that you're violating the spirit of the agreement, is he wrong? Would he be wrong to say that he'd been misled?
This is the heart of the problem: if I open a grocery, I pay the landlord a fixed rent, not a cut in my sales. That's because rent is generally seen as a commodity. Apple doesn't want to accept that their App Store infrastructure is a commodity (it's not cool to be a commodity), so they come up with this revenue sharing system. They see themselves as a publisher.
That's nice if you're a small developer, because the alternative is paying a high fixed fee.
So what would that fee be?
There's 50.000 iOs developers [0] and the app store generates about a billion in revenue (off the top of my hat). That means we're paying Apple about $300 million.
That means the fixed price should be $6.000 per year for Apple to earn the same amount (there's probably no sustainable fixed-price point).
Obviously, if they did that, Android would become infinitely more attractive, since they could offer a much cheaper service (no expensive in-house review team).
So here's the dilemma for Apple:
1 - continue with their publisher business model (percentage), maximize for profit at the cost of karma and long term risk of anti-trust lawsuits
2 - dramatically reduce cost (less or more efficient quality control), introduce a fixed fee that developers can still afford ($500?) or subsidize the whole operation more.
3 - keep the current system, but don't force developers to pay you. Sort of an honor system / convenience. That seems to work well for DRM free iTunes music.
The Apple Store, so far as I know, has some built in unsustainability because it supports update paths but doesn't have a way to charge for that service. In the long run, it will need either a new revenue source or a "trust" created by initial sales. In-app purchases probably provide this revenue source.
I think the end-game here is for Apple to create an "alternative minimum price" for apps that are free or already sold based on Apple's cost and a margin on the App Store generally. In-app purchase cuts will be charged until the total AMP has been reached.
That's probably a long way off, though. First Apple has to abandon an admittedly intuitive charging system. Second, there will probably need to be a point where the best apps are on Android and the App Store is bringing up the rear.
We could always look at it from Amazons POV. They are providing the content that makes iOS devices more desirable for consumers. Why isn't Apple giving them a cut of each device sold?