Last I looked their App Store was competitively priced, they take 30% just like Google takes 30%, Samsung takes 30%, Sony takes 30%, Xbox takes 30%, Nintendo takes 30%, Steam takes 30%.
If you're talking about having a third party app store on the phone that doesn't have to cover the costs of producing the phone, selling the phone, developing the phone's hardware, developing the operating system, developing the APIs, developing the SDKs and developing the developer tools and supporting the ecosystem services then that's hardly fair competition. Of course that other app store could provide lower rates because it's not actually paying to develop anything.
Apple have established this model for selling phones where the App Store is tied into their ecosystem. You know what is crazy? People are buying them. It is absolutely insane, it's like for 12 years now Apple have said it's their way or the highway and you know what is happening? More people than ever before have iPhones. People could choose Android phones that let them side load apps, run their third party app stores and aren't limited to the apps that Apple approves on their devices and the limitation Apple applies to them. For some reason though, people aren't picking that. People aren't choosing to go to the open ecosystem. They all must be crazy.