To hire somebody via H1B route, you need to: a) pay at least average salary for this position; b) prove that there are no local candidates available for your opening, c) prove that it is not because of your low pay rates, but because of genuine shortage of specialists with these particular skills, d) pay processing fees and wait for at least 6 months, perhaps more.
Common sense says if someone cannot freely move between jobs, who faces immanent deportation if fired, who will have much better prospects of living well in US than their home country, then this person has much less leverage and would be paid less. It is easy to test this hypothesis: do H1B holders have a much higher rate of changing jobs after obtaining visa than their peers.
Come on now. You can't actually believe this is how it works in real life.
http://www.cringely.com/2013/07/18/so-thats-how-h-1b-visa-fr...