Because the California DMV determines who gets to drive in California. The CA DMV licenses autonomous vehicles.[1] California was the first state to do this. There's a reasonable licensing system. Vehicle makers can apply for a license to autonomously test drive with a safety driver (easy to get, 50 companies are licensed), testing without a safety driver (harder to get, only 7 companies licensed), and deployment (only Neuro, Cruise, and Waymo have qualified.) Tesla's marketing materials imply that they are qualified to deploy autonomous vehicles. They're not.

[1] https://www.dmv.ca.gov/portal/vehicle-industry-services/auto...