When should you legally pass the vehicle on the right if you are on a two-way road and the vehicle ahead of you is turning left into a driveway?

This answer is correct for California. It may not be so in other parts of the US. If you are on a two-way road and the vehicle ahead of you is turning left into a driveway, you can legally go past on the right if there is enough road between the curb and the vehicle to do so. This rule does suggest that care in making that decision is needed, and will necessitate a review of the area around the two vehicles and any people walking there.