Labor is a commodity, just like coal, or produce, or manufactured goods.

When I was a youngster, field jobs in Florida were handled by blacks and poor whites. If the harvest had to be brought in in a hurry, even relatively well-off rural whites would temporarily pick oranges or strawberries because S and D drove up wages on the short term. I never worked in the fields myself, but many of my high school classmates did. In college, I worked highway, building and landscaping construction and most of my colleagues were also student/hippy types. (There were no illegals, and blacks were kept out by racism).

Agricultural black workers were concentrated in the big factory farms, and conditions were so bad out there the Feds had to periodically raid them because the workers were being kept in plantation-like conditions. You know, company goons with dogs and shotguns to make sure they didn't sneak away at night, company stores and high-interest loans to make sure they were always in debt, and cooperative local sheriffs ready to do whatever it took to keep the plantation running smoothly. They just busted a big operation like this in the Devil's Garden (SW of Lake Okeechobee) a few years ago, although this time they were not African-Americans (they're too well organized and have too many political allies). They were illegals, Haitian and Dominican blacks

But once the growers started importing foreign workers they were the only ones willing to work for the shit wages being offered. And they didn't cause no trouble, either, or they would be deported by the migras in the middle of the night.

"Americans won't do that kind of work any more" is right wing propaganda. Some Americans are working three jobs now, and their wives, too, just to pay the rent and feed the kids. They would be out there picking lettuce if there was a real Law of Supply and Demand Invisibly Handling wages. To imply they are too lazy or too scared of getting their hands dirty is an insult and a lie.

By bringing in cheap, illegal labor, by ignoring the law, and by using law enforcement to discipline unruly workers, the Bosses can pretty much violate so-called supply and demand pretty much any time they want. And they will, every fucking chance they get. These are not anomalous or special circumstances, or one of a kind violations. It is the inevitable result of the misuse of economic power and officials in the pockets of " business community leaders". And the same thing is true in any industry or business, at least in kind, if not in degree.

There are strong economic incentives to bring about these outrages, and unless they are sought out and nipped in the bud, they are inevitable. That's where the system naturally tends to go if left to itself. The Invisible Hand is usually a clenched fist...with a bullwhip in it.