There's a little more to it than being better at it. While actual job proficiency may come in to play, compensation is the larger part of the equation. I would also think there is quite a bit of difference between someone working in academia and the average joe on the shop floor. That guy running a punch press has nowhere else to go when the immigrant takes his job. It's especially true when that immigrant is illegal. I can take you to many a small to medium sized shop in the Chicago area and the overwhelming majority of the workforce are illegals working for the same money that was being paid 20 years ago. Jobs are lost, wages are suppressed,and benefits are slashed under such conditions. Hardly the democratic theme we hear about that party representing the working class.