Yes and no. They made $30/hr in Des Moines or Chicago or other cities. There were profitable union slaughterhosues in New York into the 80s. Slaughterhouses were moved out to the country to break the unions, period. “Saving money” by being closer to farms is a contrived argument. A good place to start is the book “Fast Food Nation”.
Illegals are a symptom. The problems are industrial facilities with heavy manpower requirements, high turnover, designed to operate in a way that guarantees chronic medical problems with workers, placed in places with no people.
The big waves of Mexicans chose to move to places like rural Iowa in the 90s not out of a desire to break their bodies hacking at meat at high speed, but because trade policy flooded cheap corn into the market and exploded the Mexican agricultural economy.
Rural communities have been conned hook line and sinker. Their death began when the alliance between western resource barons and southern democrats (ie segregationists) began with Nixon. Trade policy, financial sector consolidation, offshoring of industrial economy dug the grave.
I grew up in a beautiful northeast rural community. It’s a shell of what it was when I was a child. All of the dairy operations are gone, and most of the full time farms will cease operations when the owners retire. The economy runs on social security, public assistance, government workers commuting up to 90 miles away, and a couple of small industrial operations. Nobody with any ability will stick around, and that has nothing to do with people trying to escape life in Central America.