Source?
This doesn't have to be the case. But Apple's lockdown enables Google's tyranny, so there's really no other choice. On other platforms, I can install apps like NewPipe on watch YouTube in the background without needing to download anything from Google besides the videos I want. Google is not the savior of this story by any means, but they're not afraid to play Apple's game of turning iOS users into hostages.
[1] I think that there is an argument to be made that the store fee subsidizes everything that people don’t generally pay Apple for explicitly, which makes it possible for free/cheap apps to exist. I don’t personally feel like that argument reaches 30% however.
Every retail outlet gets a “cut” when you buy from their store.
Are you also as outraged when consumers can buy cheaper goods online than at a BestBuy?