Also, please be mindful of business and residential neighbors. Drivers should avoid blocking driveways and side streets while waiting for passengers. Never stop in a bus zone. As far as anyone seems to know, over the history of East Bay casual carpooling, there have been no untoward incidents. A little caution and common sense also have helped.
Passengers can always decline a ride.
For example, female passengers have been known to decline rides in two-seat pickup trucks. They simply let another passenger go first, and wait for a larger vehicle. Carpool etiquette seems to be that passengers remain silent unless the driver initiates conversation.