I don't know if it counts as a 'source' but tech companies in NYC/Seattle/SF pay $75,000/yr+ to 19-20 year old interns with almost no experience. And not as a rare occurrence, I had 10 offers at the same time any given term and so did most of my classmates.
Hardly sounds like they're being exploited and suffering due to a glut in supply. Either that or "exploitation" rates in the US are double the market rate in Canada/EU.
Except that you dont get to decide whether someone is being exploited at a certain salary or not. The Market Decides, that is how markets work. If you want to pay below market, usually the only way is to broaden the labor pool by importing workers. If that is your goal, then just be honest about it. Dont say "x wage is good enough."
Since you do bring up salaries though, after taxes, health premiums, co-pays, 75 will get you a shared 1br rent in SF. If that is good for you, great. Don't say it "should" be good for everyone, it isnt. We live in a market economy, so everyone needs to play by the rules, not try to justify market manipulations with "well, oh, that should be good for you."
You can't ask the government to protect your salary from foreign competition and idolize the free market in the same breath. The fair price of labor is at the intersection of supply and demand.
Absent government interference, that includes supply and competition from foreign workers who, surprise, by and large do not feel exploited making more in a year than their parents back home make in a decade.
I am absolutely fine in allowing foreign competition. But that is a decision the American people need to make, weighing the pros and cons. That cant happen when the primary banner is "Shortage." The conversation cannot be shortage, shortage, shortage. It should be honest: "we want to import more workers to reduce domestic salaries"
Of course foreign workers dont feel exploited -- if they did, they would not come here!
I started at $70k CAD in 2012 in Waterloo, ON right out of uni. Admittedly I had "2 years of experience" due to my co-op work terms while studying at UW. Counting for cost of living and exchange rate the US offer is probably still higher, but not 2x.
(That said, I've seen startups in Toronto offering $50k/year lol!)
As for your source -- how about common sense and the most basic econ 101 chart on supply, demand and price? http://www.investopedia.com/university/economics/economics3.... The higher the supply the lower the price.