Amazon's self-driving unit Zoox opened its waitlist on Tuesday for users in San Francisco, offering free rides, just days after Alphabet's Waymo said it will provide robotaxi rides in the same market. Zoox said it is inviting people to ride its driverless vehicles for free and share feedback under the Zoox Explorers program, to help refine the experience before the service is scaled up. Riders will be taken off the waitlist depending on their location and the addition of robotaxis to the fleet,