BTW the %30 is fine considering the service they give. They handle the international trade part of the business, which is vastly different from what Walmart does. If you were to sell directly to customers, you would have to incorporate in each and every country there is(because you need to pay taxes and comply to the laws where your clients are), which is something that Epic can do but small developers can’t. Thanks to Apple, a kid with a computer can directly compete against international corporations. Also, Apple provides many if the technology that enables these apps. There’s no comparison between what a supermarket does and Apple does.

Note that comparing markup to profit margin is apples and oranges. Comparing to a particularly low-margin provider is perhaps misleading, too.