If you had a stronger grasp on the IAP rules you'd understand that many of those services don't fall under the IAP requirement because they exist 'outside of the app' or are real world products being sold. No, you don't have to pay Apple 30% on the 12 pack of toilet paper you bought on Amazon, or the Uber, or a Cable TV subscription. So this isn't the correct comparison central to your argument.
Amazon Video - subscription outside of the app that lets you play prime movies or you can purchase or rent a movie from Amazon’s website and watch it on the app.
Amazon Kindle - you can buy a book on Amazon’s website and download it to the app.
Coxmixology - again, you can buy a comic on the website and use it on the app.
SlingTV - you buy a subscription on the website and stream video on the app.
DirecTVNow - same as above.
Google Play Video - same as Amazon Video.
Spotify - subscription you buy on the website and stream music on the app.
