So many formats, so many stores

So there I was, feeling frustrated that I only had an epub version of a book - and why's that a problem since I can read it quite well on my kobo? - and complaining about big businesses plotting to tie us to their own devices (says she, so thoroughly untied that she uses a kindle, a kobo and a tablet, depending on book and the lighting, or the location). Then I got an email from a small local bookstore and thought how those small retailers tie us to buying the books they choose for us - um -...