In March, the commission approved Google-owned Waymo's application to operate robotaxis on the peninsula – an expansion supported by the Silicon Valley Leadership Group, the Mountain View and Palo Alto chambers of commerce and some nonprofit advocacy groups, including disability and bicycling organizations. San Mateo County Executive David Canepa criticized the approval as “outrageous,” claiming it shows the commission and Waymo do not care about “the public safety of local residents.”

In San Francisco, state authorities allowed the introduction of robotaxis despite opposition from the city government. General Motors Co.'s Cruise vehicles, blamed for most of the subsequent robotaxi problems in San Francisco, were grounded by the DMV in October because the agency called them an “unacceptable risk to the public.”

Last month, the National Highway Traffic Safety Administration opened an investigation into 22 crashes involving Waymo robotaxis in Arizona, including reports of “collisions with stationary and semi-stationary objects such as gates and chains, collisions with parked vehicles, and instances in which the (cars) appeared to disregard traffic safety control devices.”

Waymo said in a statement on Tuesday that the company conducts more than 50,000 trips a week “in some of the most demanding and complex environments” and will continue to work with the highway safety agency.