They pick more than one head per hour. But if we kick 'em out the American who replaces him will want double the salary, paid health care, and paid vacation. Even then, I don't think Americans will want the jobs as much as the Mexicans.
Dole doesn't hire the people who plant/pick. They contract it out to a "Field Boss" who quotes a price per acre. Therefore Dole isn't actually hiring illegal labor.
You are disgusting. You advocate for slave labor so you can eat cheap lettuce. God forbid Americans make more money at the expense of your precious salad.