The expansion doesn't come completely out of the blue. Starbucks first piloted its delivery program in September, and has been spreading rapidly in China with 2,000 shops already delivering through local services. It's not certain whether the company will find similar success in its home country, but the combination of its familiarity with Uber Eats' considerable reach (it aims to serve 70 percent of the US before 2018 is over) works in its favor.