I can tell you how it works in the U.K., California may be similar: As an employee you have a fixed place of work. Travel from home to the fixed place of work and back home is at your expense and in your time. Travel during the day is work time paid by the employer. That’s the simple part.
Where it’s tricky is if you travel from home directly to the first ...
Between jobsites, yes but not between your home and the first/last site.
California defines the term “hours worked” as “the time during which an employee is subject to the control of an employer, and includes all time the employee is suffered or permitted to work, whether or not required to do so.” I.W.C. Wage Orders, Section 2