The Jews have a long history of moving around and keeping their own traditions: they keep their own language, dress, commerce with other Jews if possible, stress education, and generally just keep their own insular community where ever they end up. The orthodox and Hassids, while generally unoffensive, stand out like a hard on in a maternity ward. If it hits the fan, politicians want somebody to blame things on. It's a match made in heaven; they look different because of the dress, they speak to each other in a tongue that the average shitkicker can't understand, and they tend to be more successful than the average redneck since they are encouraged to think. In the middle ages, the only people on the Iberian peninsula who could count to 11 without dropping trow were the Jews (when the Muslims moved in that changed of course.) They are easy targets when some politician needs a fall guy. They are different.

Disclaimer: much of this was cribbed from my first wife, who was of Ukrainian decent and was raised orthodox.