[toyg]

They wouldn’t, simply because their position as the dominant player in ePublishing gives them a massive incentive to lock-in users. Which is what their DRM does: you cannot move books to non-Amazon devices, so you’re stuck on Kindle forever. That this also satisfies publishers is something of a side-effect.

They did the opposite with music (they actually sold simple standard mp3s, unlike what you get from iTunes) because they were challengers, not incumbents, so the priority was to attract users.

[jolux]

iTunes has not sold music with DRM since 2009.

I assure you that they care much more about you buying books from them than about "lock-in" from you using their apps and buying their devices. Proof: their apps absolutely suck and their devices are not much better. The devices exist to get you to buy more books from them. It is absolutely not a side-effect that their DRM satisfies publishers.