There's a very long history in the US of immigrant groups being terribly mistreated and discriminated against, and then over time becoming part of the mainstream and fully accepted, and then bashing whatever the new incoming group is and demanding they be restricted. 150 years ago, many were demanding the Irish go home. 100 years ago, people were demanding the Italians and Chinese go home.

It's the same deal here in Canada. Wherever the current crop of immigrants are coming from, those groups that have since become established often hate that demographic change. It's stupid, and I say this as someone who has had family here for about 400 years on one side, and thousands of years on the other.