Why no major US politician supports open borders, but the Koch Bros. do

Like many leftists, I thought we could have open borders without hurting American workers. Then a friend told me to study the meatpacking industry. A little of what I learned: Workers’ Rights in U.S. Meat and Poultry Plants | HRW: For about forty years in the middle of the twentieth century, from the 1930s to the 1970s, meatpacking workers' pay and conditions improved. Master contracts