If Apple is not providing the app store infrastructure, why do they deserve a cut?
You bought your phone, it's yours. You're downloading an app from Epic's app store. Apple has no part in this transaction anymore.
You've just described console video game hardware: Playstation, Xbox, and Nintendo. Typically the argument goes is that their hardware is "different" because the hardware is sold at a loss, at least initially. So they need a way to make that expense / cost back. But, what happens when they *do* make that cost back? Should the cost disappear? What happens if they don't sell inital systems at a loss, like Nintendo, who doesn't sell at a loss, or rarely does.
You bought the Playstation, or Xbox, or Switch or "GameBoy". It's yours. Why can't you download a game from the developer directly? Why can't developers release physical games directly? If they're not involving Sony, or Microsoft, or Nintendo directly why should any developer have to pay them anything? Why does the US and EU allow for this absolute despotic complete monopoly of their hardware.
It's the same as buying software for your computer. You buy a copy of, say, Turbo Tax, for your PC or Mac. You download it from Intuit's website, and install it. Why should Apple get a cut of that?
Believe it or not, that's because Intel allows for arbitrary code execution. But, they don't have to. Maybe you don't believe me. It's still perfectly allowable - That's what allowed (still allows) Nintendo, Sega, NEC, SNK, Sony, and Microsoft to lock their video game hardware.
Apple came up with this insane concept that they need to be paid by developers to write code for some of their devices. It's a completely insane idea that took off because obviously companies want to make more money, but the reality is if you're not using Apple's infrastructure to distribute the software, Apple doesn't deserve a single penny.
It's not Apple that came up with the concept, it's actually a legal mandate / precedence from the late 1970's / early 1980's. You have Atari vs Activision which established the necessity for "lock-out" chips or systems (which has lead to our modern day cryptographic signing). Long and short of it is that Atari lost because the Atari hardware allowed for arbitrary code execution.
And while Atari vs Activision legally enshrined / established that 3rd party development is perfectly legal and that 3rd party developers owe *NOTHING* to anyone for the code they write or sell -- 3rd party development is subjucated to the aformentioned lockout system. So a chip developer such as Intel or AMD (or system developer e.g. Nintendo, Sony, Microsoft, Apple, Google, etc) can lockout code and then license the use / execution of code.
So, while the EU has decided that Apple must allow for 3rd party App stores, unless we learn otherwise, Apple still gets to charge for code execution.