In my country, and I assume in the US, immigrants are useful to the bourgeoisie as highly-vulnerable and highly-exploitable labor. As many say, they do the hard and dirty jobs which other people don't want to do, they can be coerced with threats of deportation. And with the US Republican Party's apparent attempts to reduce offshoring and bring production back onshore, surely powerful sections of the bourgeoisie have an interest in lowering labor costs to compensate.
A popular answer from the mainstream is to simply point to White nationalism and other bigotry. Another answer is that illegal immigrants acts as a scapegoat and a way for their party to signal to citizens that they're doing something to solve their problems. And while I think these are reasonable and plausible suggestions, I want to explore other options before assuming a simple cultural explanation. For example, liberal media tends to frame Middle-Eastern conflict with the Zionist Regime (and even Western support for the regime) as religious conflict or even a racial conflict, rather than colonial imperialism.
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.
Not to mention that hatred doesn't need to be actually logical. There's a professional pipeline of liars trying to manufacture the rationale to hate, the likes of Charles Fertilizer and company.