Companies are getting their fix of cheap labor by partnering up with universities to provide them via the F1 OPT work program. They enroll foreign workers to the university and the university put these 'students' to work for the companies under the guise that they're doing 'research work' for the university. Here's an article on it:
http://www.breitbart.com/big-government/2016/01/05/industry-...
"PERM Fake Job Ads defraud Americans to secure green cards" https://www.youtube.com/watch?v=TCbFEgFajGU
How Record Immigration Levels Robbed American High-Tech Workers of $10 Trillion http://www.thesocialcontract.com/artman2/publish/tsc_22_3/ts...
How American workers are being sold out, By Michelle Malkin and John Miano, November 8, 2015 http://nypost.com/2015/11/08/how-american-workers-are-being-... www.amazon.com/Sold-Out-Billionaires-Bipartisan-Crapweasels/dp/1501115944/
http://www.computerworld.com/article/2908124/10-us-senators-...
other sources on visa abuse or fraud: John Miano - cis.org/Miano-Blog
NumbersUSA - https://www.numbersusa.com