To help you answer the titular question, take a look at the following quote from Mary Bauer of the Southern Poverty Law Center (link):

...employers have so far escaped sanctions [under Alabama's new immigration law]. One section assigns escalating penalties for employers caught hiring undocumented workers, ranging from a three-year probation for the offending company to a permanent suspension of all business licenses in the state. Officials report virtually no instances where such sanctions have been enforced.

"This law is scapegoating the vulnerable population. Cracking down on those people is a lot easier than going after businesses," said Mary Bauer, legal director for the Southern Poverty Law Center. "I don't see how we can see it as anything other than a civil rights crisis."

How are businesses that rely on cheap labor responding to the new Alabama immigration law? They're squealing like stuck pigs.

The Alabama law is directly impacting corrupt growers and others who relied on illegal labor to keep wages down. Yes, a few perp walks of those growers would be nice, but the law is clearly affecting them. The law as enforced or designed might not be directly going after corrupt businesses, but it certainly is going after them indirectly.

Rather than reducing the amount of cheap, pliable, and illegal labor in Alabama, Mary Bauer and the SPLC would enable corrupt growers to reduce wages and safety standards through the use of illegal labor.