Some advocates of increased immigration have raised the specter of higher food prices without foreign farm workers. But the price that farmers receive for their produce is usually a fraction of what the consumers pay at the supermarket. And what the farmers pay the farm workers is a fraction of what the farmer gets for the produce.
In other words, even if labor costs doubled, the rise in prices at the supermarket might be barely noticeable.
What are called "jobs that Americans will not do" are in fact jobs at which not enough Americans will work at the current wage rate that some employers are offering. This is not an uncommon situation. That is why labor "shortages" lead to higher wage rates. A "shortage" is no more quantifiable than a "need," when you ignore prices, which are crucial in a market economy. To discuss "need" and "shortage" while ignoring prices -- in this case, wages -- is especially remarkable in a usually market-savvy publication like the Wall Street Journal.
Often shortages have been predicted in various occupations -- and yet never materialized. Why? Because the pay in those occupations rose, causing more people to go into those occupations and causing employers to reduce how many people they "need" at the higher pay rates.
Virtually every kind of "work that Americans will not do" is in fact work that Americans have done for generations. In many cases, most of the people doing that work today are Americans. And there are certainly many unemployed Americans available today, without bringing in more foreign workers to meet farmers' "needs."