Here in the USA, Trumpists are very hostile towards immigrants coming from the Mexican border to the point where they infamously proposed to build a wall. The Biden administration is better in-name only, and has kept the concentration camps at the border.
Why is there so much hatred toward these immigrants? What is the material cause of this?
"Illegal" immigrants are just being used as scapegoats for the frustration of working class people with a system that doesn't even benefit them. You see, if you frame both the bourgeois gran blanc and proletarian petit blanc as inherently the same class and more deserving of rights, dignity or even power, then the small white will serve as the foot soldier to the property holder.
This has been a tried and true technique of the ruling class ever since the beginnings of colonialism, just now racial theories are no longer as attractive (but still popular), so they fall back on the legalistic sense that immigrants are "illegal" and "stealing jobs" or "bringing crime/drugs," because in fact not even the white proletarian life is particularly easy or privileged. It is just slightly better than that of the non-white (or non-cishet boyish) proletarian, and only getting worse with time, so keeping people addicted to those tiny privileges and hostile to positive change maintains a good buffer between the most oppressed and the actual most wealthy.
If you really look into the reasoning of the MAGA people, you'll see that they are in part motivated by a twisted notion of the material reality, be it jobs, crime, housing, but fail to find the actual culprit for those things and fall back on the same backwards Yankee notions they've been taught since young (race realism, Yankee exceptionalism, co-opted Christian values, hard work pays off, anti-communism). On the other hand, Democrat followers have to outright deny the material reality because to do otherwise they'd quickly lose faith in their own party. I think that's why they're so scared of people "Just Asking Questions," because they don't have answers, or how Clinton had to go "America is Already Great."
But the actual Democratic party is well aware of the material conditions:
They have, because those border camps serve as more than just racist arbitrariness. They not only serve as an incentive to keep the immigrants already in the USA in line and scared, but also have forced labour with barely any compensation and terrible living conditions. By shutting down those, Biden would be hurting the same class that put him and his party "in power," so they have no real reason to stop that. They'll just complain about it, like they did with other things like abortion, but shake their hands in the air and pretend there's nothing they could've done. They're not stupid, really, they know what they're doing most of the time.