To see why Apple’s mandatory commissions are absurd, compare phones to desktop computers. There is no fundamental difference between the two. So, why is it okay to install whatever you want and pay for it directly on desktops, but on phones it is not? The “better security” argument just doesn’t make sense in this context.
Apple is hosting, distributing, and directly marketing apps in the app store. They are reviewing submitted apps for compliance with their policies and security requirements. If you want to compare it to desktop computers, great! Compare it to the macOS App Store which… takes a 30% commission. Whether or not you personally agree that 30% is a reasonable fee, you can't simply deny that operating the app store costs mon…
They CHOOSE to do this. If there were a free and open market for app stores, competitors would pop up, who would similarly host, distribute, market, and "review" apps. And they would do it for a whole lot less than 30% and 99USD/year.
They charge 30% and restrict other installation methods because they can, but you cannot justify it based on those costs.
I firmly believe this model isn't going to last. If it didn't hurt Apple's bottom line so much, PWAs would be far more prevalent already than they are, and that's right now. In 10-20 years, this thinking will be gone. They just have to milk it as a long as they can for the shareholders.
It's their hardware, for now they can do what they want. Most consumers didn't even know about the 30%, and probably still don't. Guess who it benefits to keep that under wraps? Or convince the world they need an expensive app store to vet their apps before downloading them?
(And don't say "there's nothing like a native app experience". It's completely irrelevant. If there was a will to build it, the UX would be identical)