In the past two weeks, Amazon has suspended at least 20 used book merchants for allegedly selling one or more counterfeit textbooks.
I sell several e-books on Amazon. One of those I also published in printed form. Before I had sold a single copy of the printed book, there were 4 used copies for sale on Amazon … all of which were clearly counterfeited. I ended up terminating the printed version of the book as the problem with counterfeit persisted. Without a printed version for sale, there was no place to sell the counterfeits.
Amazon makes money on transaction fees – and makes money whether the item sold is genuine or counterfeit. Consequently, it has not been clear that Amazon has been bothered by counterfeit sales all that much.