The rules have changed last year, because Amazon (and a few others, but mostly Amazon) was exploiting loopholes to get around the regulations on book prices in France - and they've been accused of dumping practices, and of infractions to other laws on concurrence etc. Amazon was keeping the book prices legal but disguised further rebates in the shipping fees instead. IRRC, the French government now forces retailers to calculate the rebate on shipping fees as well.

Moving the activities of Amazon.fr out of France to keep going around the laws sounds very much like something a company like Amazon might do. They're little better than a Chinese company for ethics.