Communism

Immigration policy is all about having control over the supply of labor, and its cost.

Having an undocumented and potentially instantly-deportable work force helps keep wages low, and lets them be deported at the drop of a hat if there's an oversupply of labor.

Having an indoctrinated nativist / chauvinist population also creates a constituency to make deportations viable, and justify segregating "non-native" workers into low paid, exploitative jobs.

This is all really common in the US, UK, France, and Germany.

To discipline labour. It makes those who weren't deported more scared, and thus more open to accepting increased exploitation.

Because Fascists tend to get high on their own supply.

forced labor, America yearns for slavery

American here. It's probably hard for you to comprehend how deep racism goes here.

Back in the day, a slave owner would rape a slave, and then sell his own child. In other New World colonies the half caste child would be acknowledged, but the US had a "one drop" rule where any slave ancestor meant a child was a slave.

Another thing is that it's also about putting more police on the streets. If they just wanted to get rid of immigrants they'd make hiring undocumented workers a felony. If slaughterhouses/farms/oil feild owners knew they'd be sent to jail, they'd make sure to triple check the workers status. Instead, Trump et al are doing the least cost effective thing, because it means they can hire more and more cops and turn them loose.

These aren't complicated people pursuing a complex agenda. Think of it this way; Trump was at the University of Pennsylvania at the time their Business Department was really pushing computers. Trump could have hired Bill Gates and Steve Jobs. He ignored that opportunity. I can cite dozens of examples of Trump being a terrible businessman. He lost almost a billion trying to buy New York City's Plaza Hotel and made himself hated by the Manhattan elites when he tore down a beloved building after promising to preserve it.

imho you're looking for something that isn't there.

Why are you dismissing the scapegoat explanation as “cultural”? The capitalist project is essentially to convince the turkeys (the public, or voters in a democracy) to support Thanksgiving dinner (their own exploitation). To do so, they have to convince the public that someone else, and not the capitalist class, is to blame. Immigrants are a favorite target to play this role, with cost of living, low wages, high housing prices, taxes to fund social services, and more being attributed in whole or in part to foreigners or “invaders” whom the capitalist promises to remove in order to supposedly benefit the public economically.

I do think the scapegoat narrative is plausible, when people have somebody "lower" than them that they can hate and look down upon they stop looking up for answers to their suffering.

The modern political and social machine is more complex than one single agenda, there is no secret entity deciding everything for everyone, though in America the 24hr news broadcasts like Fox and CNN are awfully close to being exactly that. Rupert murdoch and his ilk are definitely master sociologists, and perhaps the outrage benefits them personally.

Humans are terribly exploitable, both from a labor and rights perspective as well as a puny meat brain will believe what you tell it perspective.

Monkey mad that other monkey come and take all banana. It's an easy narrative to accept instead of addressing the complex and corrupt distribution of wealth.

In my area, the loudest about immigrants often exploit those same immigrants for work on their homes. I saw a guy with a "close the border we're full" sign on his home using some spanish-only speaking immigrants to paint his house, no doubt for cheap. They literally had to paint around the sign demonizing them.

It's a fascist regime asserting power, I think neoliberalism and populism are not a good analytic framing. Elites still profit, the working class still suffers, but the mechanics are different. State violence must become more conspicuous. Racialized minorities are an easy target, and detentions and deportations are a welcome extrajudicial vehicle.