I really don't think you can blame Amazon for the high prices of ebooks. From the publisher's perspective, ebook prices are disastrously low.

There does seem to be quite a bit of inconsistency on the part of the publishers, though. They complain that ebooks are destroying their business models, and then restrict Amazon and other retailers to charge comparable prices for ebooks, but they don't treat ebooks comparably themselves. Ignoring the fact that releasing an ebook doesn't require physical printing and the multitude of material and labor costs associated with that, they don't seem to apply the same editorial (and typographic) effort that they do with printed books.