Well yes, but it's not quite that simple. When you flood the market with more labor than there are jobs, wage scales go down. This isn't just for lettuce pickers, but it's kind of a trickle up poverty effect. Let's say we lived in a fantasy U.S. and had no illegal problem. The lettuce wouldn't rot, somebody would pick it, but not at $6.00/hr. Now the lettuce grower either hires some kid at $12.00/hr or invests in machinery to pick lettuce. The John Deere co now needs more workers to fill the demand and so on.
I realize that it isn't so cut and dried but you get the point. You're now creating a population of middle class people not dependent on government. Before you know it we have less need for liberals. Hussein and his ilk (Roosevelt, Hitler , Castro etc) come to power because people are scared and desperate. When the economy is booming freedom breaks out. Keep people dumbed down, worried about their jubs, in a constant state of panic over one crisis or another and that's when these scum stay in power. Why do you think the crops failed in the Soviet Union for 70+ years?
At the present we have become a nation of government pensioners, parasites and "new citizens" who on the dole and purposely allowed to drain the system solely in the name of promoting socialism. In the meantime, motivation to work is no longer necessary. BY DESIGN.