Read NPR's excellent analysis at the link above.
Illegal immigration is a problem and Arizona is a state that has been impacted in many ways by the flood of illegal immigrants triggered by NAFTA. NAFTA hurt small and mid-sized farmers and businesses in Mexico and contributed significantly to the flood of immigrants experienced by AZ in the late 1990s and early 200s.
So, laws such as employer sanctions were passed, but not enforced because illegal immigration has been a kind of corporate welfare for agriculture, construction, and other industries that have exploited their cheap labor.
SB170 was supported in Arizona by a population angered by the failure to address illegal immigration. Some of the anger was xenophobic displacement, but having lived 17 years in the state I do believe that illegal immigration drives down wages for citizens in those industries where illegal immigrants work. It also has been a nightmare for ranchers on the border.
What Arizonans did not know is that SB170 was written by the prison-industrial complex. ANY LAW WRITTEN BY PRIVATE INDUSTRY WILL PROFIT THAT INDUSTRY.
The phrase to describe how government is captured by private interests is "regulatory capture."
Arizonans will now pay--and pay dearly--to house illegal immigrants in private prisons. These prisons will have every incentive to keep the immigrants detained as long as possible in order to rake in the funds.
So, while Arizona cuts funding for the mentally ill, the disabled, children, and the elderly we WILL ALL BE PAYING THE PRISON-INDUSTRIAL COMPLEX TO JAIL PEOPLE, PERHAPS INDEFINITELY, WHO HAVE COMMITTED NO CRIME BEYOND THEIR ILLEGAL PRESENCE!
The employer sanctions law could have solved the illegal immigration problem with little cost if only it had been enforced.