On a May evening, a calendar invite titled "Project Sandbox Kickoff" popped up in the inbox of some AI training contractors who worked for Uber. It was a surprise for some of them, since they hadn't heard from the company in months. "I thought, 'This is the job I had heard back about in December, and now they're finally getting back to me,'" one of the contractors told Business Insider. He had been approved to start working for Uber in December, but hadn't received work since then. For years,