27% is absurdly high, for sure, but you seem to be arguing from a position that it should be free...?

The other large discussion thread has already been linked with more specifics. The very short version is that Apple has been arguing the fees are to run their services, and the commission has historically been a convenient way to collect them. This is them collecting those fees outside of their payment systems, because legally they have to allow such a thing.

So you could release an app for "free" on the app store, and require side channel payment to really use it. You're just going to have to pay for the quotation marks.

only if you want to release your app on Apple's platform; you're free to release it on Android, Windows, Linux, Unreal, etc., each of which has their own set of fees (or none)

Apple charges 30% if you do choose. Epic charges 5%.

Apple argues that what you're paying for includes SDKs. Epic does too.

you are forced to pay Epic 5% of sales (if your game makes more than $1 million), so pretty much like Apple (fees are lower of course)