Amazon delivery drivers and Starbucks baristas are on strike in a handful of U.S. cities as they seek to exert pressure on the two major companies to recognize them as unionized employees or to meet demands for an inaugural labor contract.

Why are Amazon and Starbucks workers striking over the holidays? “This is a time when both companies make a lot of money,” one expert said.

Amazon workers have walked off the job at seven facilities throughout the U.S., including the company's Queens location in New York City, as they push for contract talks with their union.