Maybe it is the 27% commission Apple states it is going to collect when using 3rd party payment systems which could be the sticking point. Lets for arguments sake say a dutch dating app developer wants to use Amazon payment system because they want the user to be able to pay with Amazon gift cards, so the app developer codes their app so it gives the user a choice, to use apples payment system or Amazons payment system which if using Amazon's, it has the user leave the app to connect to amazon's payment system so they can pay with Amazon gift cards. Now here's the sticking point, based on this scenerio and what Apple is arguing for it that they are entitled to charge 27% commission on that transaction, even though the transaction is outside of the app and thus has nothing to do with Apple.