The big differance is that the agency has to comply with workman's comp, unemployment insurance, and probably bonding of workers.
Every agency and contractor has to comply with that, but the story that isn't being told is that there are still a ton of jobs for construction in Katrina hit areaa.
This is true. Plus liability, plus the cost doing a payroll, plus a profit.
In the nineties and early oughties, I hired temps thru an agency to protect myself and often my customers required "proof of insurance".
Overwhemingly, they are not good workers, often being winos or on drugs.. There is a certain %age of the workforce that is not employable and the congregate in the temp agencies. You can ocassionally find a good worker there but they are quickly removed from the pool because a great many employers hire temp to perm, which allows them to test hire a new employee.
In the DFW labor market, at that time, an illegal off the street was $8/hr and an agency temp was $13/hr.