Plain common sense would have made any shopper realize that the cost of food or shortage of would eventually hit the stores, when the fields could not be picked.
Slowly, the realization is hitting the public awareness, as the price of corn, wheat, tomatoes, beef, etc keep on rising and will not go back down.
Oil prices will fluctuate and affect the ability to survive. But, without the fields being picked and the produce rotting in them, the cost of food will only go higher.
Cheap labor was cost effective. Immigrants have been picking the fields and moving from farm-to-farm, back in the 1920's up until today.
The work was very hard and the weather conditions very harsh. The end consumer picking that produce off the shelf, did not stop to consider, who was behind that red tomato or that ear of corn placed in the shopping cart.
Today, they will see the difference as the crops won't hit the market, but instead lie in the field rotting in the hot sun.