> Why are they unable to find a job?

>Are they less skilled and capable than a foreign worker? If so, then the foreign worker should get the job

Are you under the impression that organizations when hiring are looking to maximize skill and disregard all other factors?

once you reach 'good enough' skill level, its a cost minimization game.

If the American costs twice as much, but the foreign worker is good enough - who should get the job?