Waymo Chief Executive John Krafcik said the self-driving vehicle company is now offering limited "rider-only" trips in Phoenix, Arizona, as it looks beyond the robo-taxis business to generate future revenue. Waymo, a unit of Alphabet, has begun offering fully automated rides, without attendants in the vehicle, to a few hundred early users of its robo-taxi service in Phoenix, Krafcik confirmed on Sunday at a dinner with journalists ahead of a conference in Detroit. He did not say when or how quickly Waymo would expand "rider-only" services. Riders signed up for the fully automated service have signed non-disclosure agreements, he said. Waymo continues to look for new ways to sell its technology, beyond robo-taxi services, Krafcik said.