You give way too much credit to "young men in good health".
They are that stupid. They aren't that smart to "give it away" and take the available money. They're lazy. Business owners would take the white guy over the Mexican every day if the quality was at least equal. Sort of like reverse-cronyism. The white business owner wants to hire the white guy but he can't, the white guy doesn't measure up, thus, he loses money for the white business owner. The Mexican is the "outsider" but because of his work performance, he catapults over the white guy for the job. Amazing if you think of the cultural and racial dynamics of it.
Let me break it down because it's quite interesting. Blacks owned the lower level, unskilled labor category in the 70's and even into the 80's...along with lower level whites who by sheer numbers contributed to the total. And the level of quality, as a general rule, was pretty good across the board. Then in the late 1980's, a dramatic shift happened with the introduction of Mexican workers, who previously in the 60's and 70's had been labeled as lazy and unproductive, now they begin to populate and make a name for themselves. Heavy infiltration begins in the 90's, still under the radar to the general public, but known to business. Add to this, blacks and white men, especially, begin to lose their edge and quality of work. Kind of letting their collective guards down at the same time, content with mediocrity. Enter the high-production Mexican laborer. Mexicans took full advantage of a lazy, bitter, selfish black & white low level labor pool always wanting more than deserved...and these Mexican workers struck it rich in America while the lower level whined! What a story. You really want me to feel sorry for America's workers? You desperately want American workers to be this mythical animal that just won't get out of bed for this equally mythical and elusive "living wage". "Living Wage" is like an Obama speech, full of nothing but sure sounds good! This generation of worker is downright embarassing and would be put to shame by the 40's, 50's, 60's, 70's employee of lesser schooling.
We're getting into a pissing contest here, you'll never see my point so the bottom line, and even you couldn't argue with it...if American workers were as great and "ball-bust'in" as you state, we wouldn't have whole industries begging for help on a yearly basis. As we speak, I picked up my latest copy of Lawn & Landscape and by-golly, what was the lead story? How are we going to fill those jobs with the H2-B guest worker program crackdown? Hmmmmm, any white or black guys out there want to mow 40 acres, 6 days a week in the scorch'in sun? Didn't think so...go back to your Guitar Hero.