I doubt that's the true motivation.
I have to say up front that if we are going to have immigration law then IMO we should enforce them. The Feds have obviously failed at this and I do not object in principle to efforts by the individual states to address the problem.
That said, I found this news report disturbing:
Prison Economics Help Drive Ariz. Immigration Law
"They talk [about] how positive this was going to be for the community," Nichols said, "the amount of money that we would realize from each prisoner on a daily rate."
But Nichols wasn't buying. He asked them how would they possibly keep a prison full for years ? decades even ? with illegal immigrants?
"They talked like they didn't have any doubt they could fill it," Nichols said.
That's because prison companies like this one had a plan ? a new business model to lock up illegal immigrants. And the plan became Arizona's immigration law.