On construction projects, workers compensation immunity is real and it is powerful. (See also this article.) Workers compensation immunity is why all general contractors should have workers compensation insurance and they should ensure the subcontractors they hire have workers compensation insurance. Workers compensation insurance becomes the exclusive form of liability for an injured worker thereby immunizing an employer (absent an intentional tort, which is very hard to prove as a means to circumvent workers compensation immunity).
If a general contractor, with workers compensation insurance, hires a subcontractor without workers compensation insurance, the general contractor’s workers compensation insurance will be responsible in the event an injury occurs to a subcontractor’s employee. The general contractor becomes the statutory employer.