There are many ways to answer. To start with, "why wouldn't they take up the jobs, even if the wages are low?" There aren't the jobs. There are twice as many wo

There are many ways to answer. To start with, "why wouldn't they take up the jobs, even if the wages are low?" There aren't the jobs. There are twice as many workers with STEM degrees as there are STEM jobs, and there are people working STEM jobs without degrees. The most classical economic response is that it's collective action: if no one takes a lower wage position then the wage will stay high. Remember, > the goal of many employers is to keep wages in check by using immigration to increase the supply of workers. Alan Greenspan certainly has made this point. Speaking at a U.S. Treasury conference on U.S. Capital Markets Competitiveness in 2007, Greenspan argued that, "Our skilled wages are higher than anywhere in the world. If we open up a significant window for skilled guest workers, that would suppress the skilled-wage level and end the concentration of income." Greenspan believes that reducing wages for skilled workers, including those in STEM fields, has a number of desirable policy outcomes. Given how active many STEM employers have been in pushing for increases in immigration, they appear to agree with the former Federal Reserve chairman that immigration limits wage growth. - http://cis.org/no-stem-shortage http://cis.org/no-stem-shortage It is the goal of most businesses to pay low wages. It is the goal of employees to earn high wages. Idealistically, the government is supposed to balance these factors for the benefit of the nation as whole. Or I can answer psychologically: from the ultimatum game we know that people will reject offers which are seen as 'unfair', and we also know that people tend to rank more highly those like themselves. Hence, giving smaller amount of money to foreign workers, instead of more money to local workers, seems unfair. You could see it as class-ist: people who went to college expect to have a middle or upper-middle class job, so won't take a job which pays lower. I know one marriage which broke up partially because of this factor. Or a debt fatigue issue: paying off high student loans on a $30K/year is much harder than on $60K/year, and being in major debt for decades can wear one down and make one irritated over the situation. Or bait-and-switch: we were told that a computer engineering degree would be worthwhile, and spent years working to get the degree, only to find out we were told a lie, and now we want to take the anger out. Or a control one: a company may prefer to hire a foreign worker, whose employment and residency both depends in part on the whim of the employer, vs. a local worker who is more free to speak out about illegal or improper working conditions. (This is an aspect of keeping wages low, but I think it's important to point out in its own right.) Or a loss-of-passion issue: you implied the only tradeoff was between employment or low-paying job and that money was the key issue. If the STEM job pays too low, people will work in other fields, even if they would rather be working in the career they were trained for and love. If you need the money for your family you'll take a boring, soul sucking job for the extra $10,000/year. The exchange rate between money and happiness is not so clear cut as you suggest.