Workers at Starbucks stores plan to go on a five-day strike starting Friday to protest lack of progress in contract negotiations with the company. The strikes are scheduled to begin in Los Angeles, Chicago and Seattle and could spread to hundreds of stores across the country by Christmas Eve. Starbucks Workers United, the union that has organized workers at 535 company-owned US stores since 2021, said Starbucks has failed to honor a commitment made in February to reach a labor agreement this year.