[kapp]

Apple considers the iPhone a single product. It has many features: some of them require extra payment. For example, you can purchase a feature that allows you to play a game about Pokemon. Apple outsources the development of some of iPhone features to 3rd parties. Some of those 3rd party iPhone feature developers mistakenly think of themselves as independent application developers. Apple mercifully allows such miscategorization because it does not really matter for them or their customers.