H-1B visas are for foreign professionals working in the US.
Employing H-2A Workers
Wages: The wage or rate of pay must be the same for U.S. workers and H-2A workers. The hourly rate must also be at least as high as the applicable Adverse Effect Wage Rate (AEWR), federal or state minimum wage, or the applicable prevailing hourly wage rate, whichever is higher. The AEWR is established every year by the Department of Labor for every state except Alaska.
http://en.wikipedia.org/wiki/H-2A_VisaThat sounds pretty sweet. What's the problem?
The problem is that H2-A visas are assigned to employers, not employees. An Employer can get an H-2A visa for some number of foreign workers. Names are not required, the employer gets to decide who is covered and who is not covered by the visa.
If a worker comes to the US under an H-2A visa, he is here at the will and pleasure of his employer. If the employer chooses to underpay the worker, and the worker complains, the employer can fire the worker and replace him. The worker automatically and immediately becomes an illegal alien in this country. He has no recourse, he has no choice.
Under Arizona laws, it is a crime to be fired from your job if you are here working under an H2-A visa.