There's plenty of similar discrimination going on already in trades in professions. Essentially, doctors or unionized skilled workers prefer to give openings in

There's plenty of similar discrimination going on already in trades in professions. Essentially, doctors or unionized skilled workers prefer to give openings in their profession to their kin. With "discrimination" based on nationality it's the same thing, except that you're giving preferential treatment to your fellow Americans. It's not hard to see why given that, as an American, you and most/all of people you care about (family, friends) are likely Americans as well. It's just taking care of people who are important in your life.