I'm not versed in legalese, so maybe I misunderstand. Isn't it reasonable that Apple receives money for a service they provide, that costs money to run?
Think about it this way: totally free apps with no IAP get reviewed by Apple too, and there's no charge to the developer except the $99 Apple Developer Program membership fee, which Epic already pays too.
Yearly fee. And about $500 a year in hardware depreciation, because you can reasonably develop for Apple _only_ on Apple hardware.
This is _way_ more than Microsoft has ever charged, btw.