Apple made a guide for all the apps you can get if you don't want to use its own

Quite a nice website from Apple in response to Spotify and others that have questioned the size of the slice that Apple take from purchases made through the App Store.

I still use lots of the default apps on my iPhone and yet there's no shortage of competing apps trying to get their cut of your screen time. Is 30% fair? I'm not sure but I don't think anyone can truly claim it's stifled competition. With Spotify competing directly with one of Apple's core services, you can understand why they don't want to give their competitor a cut.