I'm fairly certain that it's illegal to pay someone for less than two hours of work [1 and 2] in California, so the practice of just doing a couple rides on your way home from dropping the kids off or hitting up peak rush hour for the bonus rate would be illegal.
1 https://www.dir.ca.gov/dlse/FAQ_ReportingTimePay.htm
2 https://blog.accuchex.com/california-labor-laws-minimum-work...