Because Europe has always hated Jews for centuries. The Catholic run places always disliked them badly. They were chased out of England, the Spanish rooted out crypto-jews in the inquisition, the French happily assisted the Nazis in deporting them.
A solid case can be made that historically, the French have been much more anti-Semitic than the normally blamed Germans.
But Mark Twain explained it best.
http://classiclit.about.com/library/bl-etexts/mtwain/bl-mtwain-concerningjews.htm
Twains explanation, followed by the stupidity of being on autopilot explains it best.