IAP is only required for purchasing digital content. This is why e-books, music, movies, game content and anything else you consume or watch on the phone requir

IAP is only required for purchasing digital content. This is why e-books, music, movies, game content and anything else you consume or watch on the phone requires IAP. Purchases for services or physical goods can be handled separately. Amazon has an app where I can buy physical stuff, but I can't buy Kindle or Audible content within the app.