That's one thought, shoeless.
But just a wage increase won't bring them out of their slave-like conditions. If we really wanted to bring those wages up to par with the rest of employment, we will have to add health benefits, unemployment benefits, sick time, time paid off, and many other perks found elsewhere.
But if we were to do as you say and raise only their wages, we would necessarily double or triple the cost of produce going to our stores. The stores would, in turn, make sure that they passed the costs onto the consumer. Americans are very good at knee-jerk reactions and they'll very likely kick out of office anyone who caused such a sharp increase in the price of their vegetables.
Here's one case to consider about this:
A few years ago, Gray Davis, then governor of California, raised the cost of renewing one's vehicle regstration. He actually raised it a whole lot. The people of California rose up almost in unison against him and for only the second time in US history, had a recall election of an incumbant. He was summarily kicked out of office and a foreign former body builder and actor was placed in his place. Apparently, those are the current requirements to become governor of the state.
No one bothered to look at the events that brought this whole thing about. They were mad as Hell and wanted Davis to pay for it. Consider the actual facts of the case:
1. Enron, that darling energy company that the Bushes loved so much, had recently been caught price fixing electricity costs for Californians. They manipulated power plants in order to charge exhorbitant prices to California. Our budget was decimated and we went through many periods of brownouts trying to conserve as much as possible.
2. The people of the state of California had already put in the budget provisions that should California not be able to pay all its bills with the normal revenue, the governor had the power to increase certain sources of revenue, namely the registration costs.
3. Californians became so angry that they decided to recall the governor.
4. The news media and the federal government kept a tight lip on the real causes for this huge expenditure. They never mentioned that the real culprits are Enron and they caused this whole thing on purpose.
5. About a year before the recall, members from the federal government, Enfon and Ahnuld met to discuss his ascension to governor.
6. There was no mention of the root cause of the problem during the entire recall process. Enron was only convicted of its crime way after that fact.
6a. Here are two interesting developments about Enron: (1) the CEO of the company mysteriously died just after being found guilty. Since the judicial case was against the CEO of the company, and not Enron itself, this meant that the widow didn't need to fulfill her late husband's fine; (2) Most of the Enron case (and just about every other SEC case that was pending at the time) was destroyed in 2001. All the pertinent documents were destroyed forever. It was not just any day in 2001. It was September 11, 2001. All these SEC documents were located in WTC7. By the end of the afternoon, the SEC lost all or nearly all of its investigative work on dozens of cases in progress at the time.
Things that make ya go hhhmmmmmmmmmmmmm.....................
Back to immigration, any politician who causes such a huge increase in the price of produce across the US will be summarily tarred and feathered. No one will be there to remind the public that these workers were slaves before.