The Prussians were "fine"[0] with travelers as long as they were second-class citizens who didn't have access to welfare. As soon as citizenship stopped being a requirement, they were no longer fine with them and "they just want to live her to get our money" became a compelling narrative to fuel the bigotry against them.
As a German it hurts to admit this, but Europeans are still extremely bigoted against travelers (and yes, if you prompt them, they will have very good rational reasons and cite crime statistics, which may sound familiar to Americans and suffers from the same limitations of surface-level analysis of social problems). It's just that we successfully deported and murdered enough of them in Germany that the discourse usually only involves Sinti and Roma people nowadays.
[0]: "Fine" in the sense most conservatives say they are "fine with homosexuals", i.e. "as long as they keep to their own".