Does anyone have any ideas?
Do we know that is the case?
It is according to Thomas Sowell. Perhaps I need to reread that part of Economic Facts and Fallacies to see if he provides an explanation.
If it is actually true, I would take a look at the tax code. By providing people with benefits that dont count as income it lowers the tax liability for the company (payroll taxes). It also benefits the employee by keeping them in a lower tax bracket. Without a tax on income companies would likely pay people straight up for their labor and let the employees provide for their own insurance and retirement.
The tax code distorts all sorts of things in the market.
U.S. real wages: http://www.mindcontagion.org/html/real_wages.html
U.S. non-farm business sector compensation: http://upload.wikimedia.org/wikipedia/en/a/a5/US_real_compensation_1964-2005.gif
Real wages down: High unemployment means more supply of workers. By law of supply and demand, more supply of something means it gets a lower price, meaning lower wages.
Total comp up: By law of supply and demand, higher supply of paper money [aka quantitative easing, and other euphemisms] means it has a lower price. “Price” for money means how much it can purchase. So paying the same or even a lower real wage needs more paper money than before.