You do, that's the crux of the matter. Apple can happily claim that 30% is the overhead cost of providing the subscriptions service, that's within their right. Looking past how ridiculously high 30% is the fact that they are so hostile to apps having users pay via means that aren't the app store is the issue. For example Spotify aren't allowed to even tell people in the iOS app that they can subscribe with a credit card on the web without facing rejection.