Self-driving startups like Cruise and have begun testing their driverless cars in some parts of California in the past year with an additional feature: human operators.

While there is no driver behind the wheel, the passenger seat is occupied by a safety operator who "has a red button that can stop the vehicle just in case anything happens," CEO James Peng said.

The operator will be removed next year when, whose investors include Toyota Motor Corp., plans to deploy its driverless ride-hailing vehicles in certain areas of California. Still, a remote operator will monitor vehicles and provide guidance when the vehicles run into trouble, Peng said.