According to California's Insurance regulator:

The CALIFORNIA LOW COST AUTOMOBILE INSURANCE PROGRAM (CLCA) began as a pilot program in 2000 for residents of Los Angeles County and the City and County of San Francisco only.The California Legislature wanted to address the problem of uninsured motorists in the state, proposing the theory that most uninsured drivers in California go without liability insurance because of the cost, and that if affordable coverage was available, many drivers would purchase it.

In 2005, the California Legislature passed Senate Bill 20, which expanded the Program to the counties of Alameda, Fresno, Orange, Riverside, San Bernardino and San Diego, effective April 1, 2006.This legislation also authorized the Insurance Commissioner to launch the Program throughout the state upon determination of need in each county.

• Effective June 1, 2006, eight additional counties were introduced into the Program: Contra Costa, Imperial, Kern, Sacramento, San Joaquin, San Mateo, Santa Clara and Stanislaus. 
• On March 30, 2007, the six additional counties of Merced, Monterey, Santa Barbara, Sonoma, Tulare and Ventura were added.
• On October 1, 2007, twenty more counties were added: Amador, Butte, Calaveras, El Dorado, Humboldt, Kings, Lake, Madera, Marin, Mendocino, Napa, Placer, San Benito, Santa Cruz, Shasta, Solano, Sutter, Tuolumne, Yolo and Yuba. 
• On December 10, 2007, the final 16 counties of Alpine, Colusa, Del Norte, Glenn, Inyo, Lassen, Mariposa, Modoc, Mono, Nevada, Plumas, San Luis Obispo, Sierra, Siskiyou, Tehama and Trinity were added, making it a statewide Program.

The program is administered by the California Automobile Assigned Risk Plan and policies are written by California Licensed Insurance Companies.

The CLCA program is not subsidized by taxpayers. Rates are set and adjusted annually in each county so that the premiums collected are sufficient to cover losses and expenses in each county.

To be eligible:

• Applicant must be at least 19 years of age or older and a continuously licensed driver for the past three years.
• Applicant must qualify as a good driver.
• Have a vehicle currently valued for $20,000 or less.
• Must meet Income eligibility requirements.

You can visit the California Insurance Department for more specific information. It is possible that government regulation and intervention may raise the rates in California, instead of solving the problem of uninsured motorists in the state. Typically, when the government tries to add more unnecessary regulation or tries to segment a free marketplace, insurance rates become higher for everyone.