You're Amazon. You ARE datacenters. So why the ever-living-hell can I not buy FLAC-encoded lossless tracks? There is an utterly negligible cost in providing this content, its the only market which still moves CDs so there's obviously demand, but no one is touching it?
I'd point out, that Apple doesn't event support its own lossless codec for downloads, and they are arguably the market leader.
Actually, the reverse. Apple's goal is to sell more hardware; software/music/books/videos just exist to draw users into the ecosystem and keep them there. Apple doesn't care where you get your content (though iTunes & iBooks makes it more "sticky"), so long as you use Apple hardware and buy more of it. That iTunes & iBooks & etc make Apple truckloads of cash is just a bonus.
Google's MO is to gather as much info as possible. Selling music & books just gives Google more data to mine. Again, the truckloads of cash is a great bonus.
Amazon, however, is all about selling content. The Kindle line (Fire phone included) exist just to persuade customers to buy more - hence the magic find-and-buy-this button and other cart-greasing features.
BTW, I didn't realise that they were renaming iBooks to a daft name like Beats. Thanks.
I don't have an Amazon tablet, but my Kindle has ads for completely uninteresting books right on the home screen.
Google pushes Google Play for music and books. Similarly it's in Google's interest to push people to the Google storefronts.
Apple and Google make up basically 100% of the smartphone/tablet market. If Amazon doesn't get in there they may slowly get pushed out. They don't lead in music (iTunes?) or video (iTunes/Netflix?) or apps (Apple's store), and they certainly don't want to lose their position in books.