There's a very simple law: You can't use a strong position in one market to enhance your position in another market. Simply put, the entire tying up of payments

There's a very simple law: You can't use a strong position in one market to enhance your position in another market. Simply put, the entire tying up of payments to Apple is classic anti-competitive behaviour, and there's little chance the courts won't put an end to it. Same will happen with Apple using private APIs for its store owned apps. That said, it's very unlikely the courts will interfere with the 30% fee. There are no legal grounds for demanding a smaller fee.