Plagiarism and how Amazon's tools impact it

I just heard a story Sunday evening on NPR about the impacts the current ease of publishing presents us. The story opens with an author of erotica finding herself being undersold by an e-book with an oddly titled name. When she does a little investigation, it turns out this other book contains exact plagiarisms of Dracula.  Another author who sells his work on Amazon found his work was being plagiarised and sold on Amazon with another author and title. When he contacted Amazon to let them this know it was happening, Amazon did nothing. I realize that plagiarism and intellectual theft happens, just see all the angry people when a file sharing website is closed down. But it had never occurred to me that a major retailer like Amazon would also be selling plagiarised work.
Something else to consider when buying online!