Janitors and security guards who work for contractors in California earn roughly 20% less than their colleagues who are employed directly by companies, according to a report by the University of California’s Center for Labor Research and Education. The wage gap has grown along with the number of companies specializing in those services; janitorial jobs rose 44% and security positions rose 83% between 1990 and 2014. Contractors often do not pay overtime or minimum wages, nor offer health insurance, often classifying employees as independent contractors. Workers seeking redress find a system complicated by the fact that contractors often subcontract, leading to uncertainties as to who is responsible for their working conditions. Companies now need to evaluate more closely the contractors they hire, as the NLRB ruled last year that employers may be found at fault for labor violations incurred by contractors.
See "Janitors and security guards are paid 20% less when they're contractors, report says", Shan Li, The Los Angeles Times, March 9, 2016