Waymo will open its self-driving taxi service to tens of thousands of people across 47 square miles in San Francisco, a major expansion of the company's self-driving ride-hailing business. Last August, Waymo and its self-driving rivals received approval from California regulators to operate their commercial services around the clock. The vote is a major victory for the tech industry, which has been battling criticism that its robot cars occasionally impede emergency vehicles and cause traffic jams.

Waymo spent at least $1.1 billion on self-driving cars between 2009 and 2015, and that number is sure to grow exponentially in the coming years. Waymo will need to significantly increase revenue if it hopes to turn self-driving cars into the profitable business that technology prognosticators have been betting on for years.

To be sure, Waymo's service isn't yet available to anyone who downloads the Waymo app and wants a ride. The Alphabet-owned company is admitting passengers on a waiting list and expects it to be completed soon.

Waymo spokesman Christopher Bonelli said in an email: "This expansion applies to riders who currently have access to our service, as well as all riders who will be added to the wait list in the near future. We are still seeing very strong demand, so we want to scale in a responsible way to maintain the quality of service and a good user experience."

Scaling responsibly is a keyword as Waymo faces huge opposition, not just from residents but from city officials and law enforcement. The city's transportation agency, fire and police departments have all logged complaints about the robotaxis and called on the state government to delay the rollout. Residents have expressed concern that, beyond just traffic, the cars could hurt jobs or undermine overall efforts to reduce car use.

Waymo needs to balance the concerns of critics with the need to scale up so it can launch similar self-driving taxi services in other cities. The company also has operations in Phoenix and Austin and is piloting a self-driving taxi service in Los Angeles. The company also plans to deploy the next generation of driverless vehicles next year, an electric minivan produced by Geely's Jikry unit.

For Waymo, self-driving taxis increasingly look like its only revenue bet. The company recently paused its self-driving truck project, after spending hundreds of millions of dollars on the project.