Looks like they don't like the fact that some subcontractors aren't union folks. Now the admin sicks the labor dept on builders and their army of regulators. All in the guise of "fairness" of course.
"There has been a movement afoot in many instances fueled by the unions to force the subcontractors to be employees of the builders, because the next step is to unionize them," said Mr. Howard of the National Association of Homebuilders."
U.S. Hits Builders With Pay Probe - WSJ.com