>It's not really comparable because Amazon never did anything to try to stop anyone from buying books through any other channel.

Neither does Apple. Amazon prevents all of their sellers from selling their goods at any sort of discount anywhere else (including through direct-to-consumer channels).

>The platform they do own, AWS, unlike the iphone, is perfectly open to competitors to Amazon's retail business.

It's not apples-to-apples comparison. Here's a better one ... Amazon will gather competitive metrics from sellers on their marketplace (i.e. their 'partners' and 'costumers') and then launch a competing product, undercut them on price, rig their search (to prioritize their product) and ultimately drive them out of business.

Apple is bad, but their terribleness is limited to the Mac-iOS ecosystem ... Amazon is way worse.