It absolutely is, and for some goddamn reason everyone always gets mad at the immigrants instead of the bosses.

Much the same as in a strike when workers get mad at scabs. The person right there in front of you is looking out for their own best interests and in those circumstances that is to your detriment. Capital uses immigrant labor partly for simple price reasons and partly because those workers interests really are different from the locals and their lack of local connection makes them a viable slow motion scab workforce.