I do think we need to completely separate the need for immigration reform from the notion that there is, specifically, a shortage of scientists and engineers. I think the case for more liberal general skilled immigration is vastly stronger than the case for worker-sponsored visa programs designed to remedy an alleged shortage of STEM workers - however, the second is much more appealing to the short term interests of private corporations.

At my core, I am generally opposed to ever granting a private corporation the power to bestow US residency or a green card on a individual, and I'm actually suspicious of allowing universities to do this as well. I think a corporation should offer a job, and a university should offer a degree. This way, the markets will correct if the job or degree is not attractive to people with the freedom to choose (say, dentistry or pharmacy school over a master's degree in structural engineering, an MS in nursing rather than an MS in computer science). I also firmly believe that when non-government institutions acquire this power to bestow US residency, they use it as a crutch, and by delaying those market adjustments, delay the day of reckoning [1] to the point where high tech employers would be truly shocked by what it would take to draw highly talented people away from other fields.

One possible approach would be to abolish employer-sponsored work programs, but create a comparable number of spots for skilled immigrants. STEM background counts, but is not given special consideration over other types of skilled workers (in Australia's system, I believe a licensed plumber gets 60 points, an IT worker 40-60, depending on qualifications).

That said, controlling government is wildly profitable, and lobbying is one of the best returns on the dollar imaginable. If high tech can profit by controlling the immigration system through their own very privately run HR departments, you can bet they'll make every effort to do that.

[1] as an example, congress recently considered legislation to solve the shortage of Americans getting grad degrees in STEM fields (they excluded certain life sciences). Think about what it takes to get a PhD from an elite program in engineering or physics. Top grades in an extremely difficult undergraduate program, high GRE scores perhaps including a subject test, and survival in a graduate program with attrition rates between 33%-50%, with an average completion around 7 years! Compare this to the process of becoming a dermatologist. You need to get good grades and do premed, which is rigorous, but not as rigorous as majoring in Physics or many other STEM majors. You need to score high on a standardized test (that does require specific preparation and subject knowledge). Graduation rates for UCSF medical school are above 99%, almost always in a predictable 4 years. Residency for dermatology is 3-4 years - it's completive,and you may not get it, but remember that we're comparing this to PhD attrition rates of 50% in many fields. Starting salaries are about 280,000 a year, and go way up as you gain experience, 45 isn't considered "old" at all, and the average dermatologist works a little more than a 40 hour work week. So, what would it take to get a student who is equally interested in both fields to want to do a PhD in Physics instead of becoming a dermatologist? This is the kind of sticker shock employers may be looking at.