Amazon doesn't sell Kindles in their iOS app to avoid the in-app purchase cut to Apple. The app doesn't even have a link to Amazon's site since that's forbidden

Amazon doesn't sell Kindles in their iOS app to avoid the in-app purchase cut to Apple. The app doesn't even have a link to Amazon's site since that's forbidden by Apple's terms. But yes, they make money indirectly from customers like me who visit their website to buy books so we can read on our iOS devices.