Presumably it's because the publishers are paranoid about piracy and/or people who want DRM-free books are a minority. I was actually surprised when I bought a

Presumably it's because the publishers are paranoid about piracy and/or people who want DRM-free books are a minority. I was actually surprised when I bought a book on an online bookstore yesterday and was given the option to download it as an epub in addition to reading it in the Play Books app. Apparently that's a flag that anyone can set, but most authors/publishers choose not to.