I work at a run of the mill SaaS company. We have 60% H-1Bs devs here as contractors from a certain contracting company (more in QA). They live paycheck to paycheck. I get paid, literally, twice as much (I've seen the H-1B Labor Condition Applications for ones we hire directly--The contracting companies pay likely about as much but take some 20% of their salary).
We don't hire them because they are particularly talented. I've been on interview calls with ones from the contracting companies, all their resumes are the same [3]. They are just code monkeys. Our company does it to save costs, period. Upper management knows nothing of the mythical man-month.
The system is being rampantly abused.
[1] - https://news.ycombinator.com/item?id=13521791
[2] - https://news.ycombinator.com/item?id=13525766
[3] - http://www.vocativ.com/money/business/theyll-sponsor-america...