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?
Trump supporters are generally virulently racist. The working class ones blame their problems on oppressed groups like immigrants and the powerful ones stoke hatred against oppressed groups like immigrants to distract from the part that they play in deteriorating the material conditions for the working class. The rhetoric used against undocumented immigrants involves them competing with the white working class for lower skilled jobs and driving down the wages, them taking advantage of public services without paying taxes and so on.
Ironic because immigrants are generally doing the jobs that no one wants. Like backbreaking crop picking, raising livestock, and most farm work, really. When there's a shortage of immigrants this work doesn't get done because white people will not take these jobs, period. There's no competition happening there.
Undocumented immigrants also DO pay taxes. Even though they can't use most of what they're paying for. So they're not taking advantage of public services, they're subsidizing them for everyone else.
Americans that are racist against Latin people know that they benefit from their oppression despite what they say. The wall is a symbolic gesture, an announcement for immigrants to know their place, but it's never going to actually be built. Because keeping them around as second-class not-citizens makes the lives of whities so much cheaper.