Both the Apple App Store and (I believe) the Google Play Store have requirements that any digital goods purchased through an app that's distributed through the

Both the Apple App Store and (I believe) the Google Play Store have requirements that any digital goods purchased through an app that's distributed through the App/Play store use the payment system provided by Apple/Google, which takes a 30% cut in most cases. This is a big deal because both Apple and Google have been fighting to keep that 30% cut for years, despite the fact that neither company is really providing much value as a payments provider; they're just extracting rent from their monopoly position as the distributor for apps in iPhone/Android land.