So Amazon brought Comixology a little while back. You didn't think it's going to let Apple and Google profit from its in-app purchase, did you?
In a future update, Amazon is taking away the in-app purchase options for the iOS app and tweaking the payment method to go through PayPal for Android.
Not surprising, given how Amazon works with its Kindle apps on both platforms. Apple pretty much disallowed in-app book or reading purchases for the Kindle app to ensure that its own eBook app and store got priority. Guess you could say it's tit-for-tat in Comixology's case.
You can, of course, still buy comics as per usual. It's just that the method will differ and force users work a little harder to buy their latest X-Men or Spider-Man comics. Talking about pissing off your user base.
The iOS app at the moment considers comic purchases as in-app purchases but once Amazon makes the changes, users will have to login to the Web storefront of Comixology.
Android users will make in-app purchases as usual but they will have to use PayPal instead of Google's own purchasing platform.
You could argue that for users this is an inconvenience and it is unnecessary for Amazon to make the changes in the first place. But can you blame the company for not wanting to share profits with Apple and Google? It makes business sense and seeing as there are no real competitors for the app, Amazon can get away with this...for a while.