It doesn't have to be a "cut". They could simply charge developers to host in their store. Because they started with this model doesn't mean it's the de-facto correct or moral option.
AWS doesn't charge for servers based on how much a company makes using their resources, they charge for the resources used. Why should Apple be any different?
Two-sided marketplace can charge whatever it wants, it's their marketplace. They need to charge whatever they feel is right to make it worthwhile and provide enough value to both sides so that the marketplace can exist and grow.
Apple released their marketplace over a decade ago with 30% fee.
Developers ran away from Symbian, webOS, Windows Mobile, Windows Phone and RIM to Android and iOS, thus proving that the charge is fair and the marketplace provides the right value for the cost to be part of it.
RIM, Nokia, Palm and others tried to do something similar, burned billions, but the market (via consumers and developers) has spoken, and those companies are now history and a part of business curriculum how innovation and changing the status quo can disrupt existing markets.
A decade later, after playing part in allowing Google/Apple duopoly to exist, developers now feel they have a basic human right to have access to a marketplace of billions consumers for free.
i.e. the % cut they take for the non-trivial service of billing and all of the overhead, for marketing and distribution etc..
People use the App Stores as primary point of entry, they trust it, their CC's are in there, and they have volume.
All said, if there were other app stores allowed to play ball, Apple/G could probably charge 8-10% and people would pay it.
They could require that any app downloaded from their store use their billing service, that's reasonable.
These are platform monopolies, they're bad for everyone.
If the web were to have been controlled like this, it wouldn't remotely exist in it's current form.
No web engine but their own:
> 2.5.6 Apps that browse the web must use the appropriate WebKit framework and WebKit Javascript.
> 4.7.1 [...] only use capabilities available in a standard WebKit view (e.g. it must open and run natively in Safari without modifications or additional software); and use WebKit and JavaScript Core to run third-party software and should not attempt to extend or expose native platform APIs to third-party software;
No apps allowed to stream content not individually reviewed by the App Store, despite the lack of security risk that comes with streaming instead of installing outside apps:
> 4.9.1 Each streaming game must be submitted to the App Store as an individual app so that it has an App Store product page, appears in charts and search, has user ratings and review, can be managed with ScreenTime and other parental control apps, appears on the user’s device, etc.
> 4.9.2 Streaming game services may offer a catalog app on the App Store to help users sign up for the service and find the games on the App Store, provided that the app adheres to all guidelines, including offering users the option to pay for a subscription with in-app purchase and use Sign in with Apple. All the games included in the catalog app must link to an individual App Store product page.
Blocking "side loading" of apps from the web, forcing streaming of apps to be shoehorned into the App Store individually, locking down all web functionality to Apple's implementation ...
Apple is not a fan of old and new web capabilities that compete with its App Store. This is a problem for general computing innovation.
[1] https://developer.apple.com/app-store/review/guidelines/
This is already the case with most apps? Everything is a demo, with a subscription IAP.
The post-purchase 30% cut amounts to adding or enabling content/function to the app post-purchase, meaning developers can put off charging users for some of the app until later, at which point it's fair for Apple to still get their cut - lest developers (like Epic) give away the app and effectively charge for the app later to bypass the 30% cut. E-books are, in a reasonable sense, part of Amazon's Kindle app. Movies are part of a video rental app. Power-ups and other features are part of the Fortnite app. As Apple is only charging for what is in essence part of an app, not for non-app stuff like chairs or rides or food, it's a not-unreasonable attempt to prevent developers from giving away apps and charging later to avoid the 30% App Store service charge.
Seems this is a moment that Apple, Google, and others really need to win, lest practically all apps be "free with in-app purchase to do anything meaningful".