That's a really poor analogy. The game developer sets a price in which they will sell to the retail store, the retail store decides to price it at their chosen margin (and it definitely isn't 30%). The retailer also doesn't get any revenue from in-game purchases or DLC's. It costs a retailer more money to have shelf space for the product across hundreds or even thousands of stores than it costs apple to process a payment, which is literally all they are doing, and all they want to do. Epic's servers are more than capable of handling updates and payments as well. Merchant accounts don't charge over 5%, how can Apple justify 30% of an in-game purchase? There is no cake to be eaten here...