Construction is a racket and DOB is bureaucratic mess here in NYC that drives up cost. Plenty of licensed contractors subcontract or "lend their license" for a fee to non union/undocumented skilled workers. Then there are expediters who know how to navigate the DOB and have connects to speed things up or find contractors willing to do the above.

Point is, construction is expensive if you use union licensed workers who themselves might subcontract to whomever but charge you the higher rate. Why not skip the union guy to save