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.

Less than a week before Christmas, Amazon and Starbucks employees are striking as their respective companies refuse to meet union demands.