According to Cornell University's Margolies, unions haven't been able to get enough workers to organize an election to form a union.

Workers at Starbucks and sandwich store Jimmy Johns made some headway, but those efforts didn't go anywhere.

Margolies said this is part of a larger movement of low wage workers to improve their economic positions and treatment on the job. Last week, hundreds of Wal-Mart workers protested on Black Friday against retaliation after speaking out for higher pay, fair hours and more affordable health care.