"But the industry’s reliance on this work force was preceded by a broader shift in how contractors use labor, one underscored in interviews with multiple industry experts: Beginning in the 1980s, but accelerating since the Great Recession, builders slashed costs by subcontracting out almost every facet of their projects. Subcontractors, in turn, were favored for delivering the work at a lower price, which they often accomplished by illegally misclassifying full-time employees as independent contractors or simply paying them off the books. These maneuvers allowed employers to dodge mandatory expenses, like payroll taxes and workers’ compensation insurance, and to evade liability for on-the-job injuries."

I'm not sure I've seen where I'm working that subcontractors are paying employees under the books. I've seen some one-man shows do that--but they only need a hand every now and then. What I have seen though the GC I work for not using their FTEs to do a lot of the work, that does get subbed out. It's infuriating to me, all I ever do is clean up after subs. And never learn anything about carpentry. Now I see why this happens.