You mean for Apple to charge that on top of the Visa charges, which Apple is paying out of the 30% now, I assume? Apple is the merchant of record for App Store

You mean for Apple to charge that on top of the Visa charges, which Apple is paying out of the 30% now, I assume? Apple is the merchant of record for App Store txns and pays all the transaction fees, as well as all their other costs, out of the 30%. (I don't know how much all that adds up to, but the total is strictly greater than sum of the credit card fees.)