After 19 months of piloting a volunteer program, Google is officially launching its self-driving taxi service Waymo in Arizona. Now open for commercial use, Waymo will let customers summon self-driving minivans by a smartphone app just like an Uber or Lyft. The service is available 24/7 in the Phoenix suburbs. “Self-driving technology is new to many, so we’re proceeding carefully with the comfort and convenience of our riders in mind,” Waymo Chief Executive John Krafcik told the Washington Post, adding that Waymo-trained drivers “will supervise our Waymo One vehicles” for an undisclosed period. Ride prices will vary based on time and distance and are still being worked out by the company.