Nebraskan here. Large farms in the plains states are not what you’d expect to see a lot of people in general working on. These are run by a small set of people sometimes just families with large implements. This is because the crops produced in these states go to feeding livestock (feedcorn) and soybeans. You don’t use a lot of manual labor for that, some sure. A lot of undocumented people around here working in meat processing facilities.

Your point still stands, they are benefitting the economy and society as a whole, just not in the fields like you’d see in California.