I was at a party and was challenged on the question of immigration of Mexicans. The question was "Why do we believe in the free movement of capital and goods but not labor?"
My answer is that we don't actually have a conceptual problem with free labor movement, we have simply not honestly tackled the problem. The number and importance of the people involved is growing rapidly.
We have plenty of free movement of labor across boundaries. I personally have earned income in more than a dozen countries as a business consultant, author and lecturer. I paid taxes in each country on my earnings and I traveled on a tourist visa. I would guess that private contractors, employees of consulting firms, American employees of firms operating overseas who are traveling on tourist visas generate overseas earnings of several hundred billions of dollars and that a comparable amount is earned by foreign professional workers working in the U.S.
What is the difference between me and the "illegal Mexicans and others" who work all around me? Two differences: one, my work is short term and can be done on a tourist visa, the "illegal Mexicans and others" are here for longer periods of time and there is no appropriate visa for them to get. Two, I pay taxes to a legal tax account because I deal with corporations who can legally pay me or pay a business entity that represents me. The "illegal Mexicans and others" have to pay taxes to imaginary Social Security numbers because they don't have appropriate work visas.
As we become more honest and politically open about this issue we will battle out the issue in the political process. There is no reason that I and other white collar and professional workers should freely travel the globe, earning money and paying local taxes when blue collar and agricultural workers can't. Of course there is a middle group, white collar and professional workers on long term projects. They are squeezed into a few hundred thousand limited American H-1b visas. That is a disgrace.
The whole issue must come into the open, be discussed, fought about and turned into a policy of open labor movement across borders with everyone paying appropriate taxes.