The defensive style driving of the Google car won't work in San Francisco where you literally have to break the law in order to turn left (by stopping in the intersection and often finishing the turn on a red).
I don't have the California Vehicle Code in front of me, but I'm pretty sure about this because the situation arose during my road test to get my first license (yes, I still remember this, even though it was almost 40 years ago!). I had entered the intersection to turn left, and when the light turned yellow, the tester lady said "clear the intersection" or words to that effect. (I passed.)
Anyway it has to be that way -- you can't have cars stuck in the middle of the intersection while cross traffic tries to go around them!
> If you are turning left, make the turn only if you have enough space to complete the turn before creating a hazard for any oncoming vehicle, bicyclist, or pedestrian. Do not enter the intersection if you cannot get completely across before the light turns red. If you block the intersection, you can be cited.
I haven't lived in a lot of states but they've always said "one car can enter the intersection and wait to turn left." Implicit is the assumption that they have some place to be when the opposing traffic clears.
It also doesn't make sense that not even one car per cycle is allowed to turn left across such a traffic flow. You could have sat there for hours following that advice.
A few years ago the Colorado (yes, I know, not California, but bear with me) driver's education handbook said that this was legal and advised... Now it too says the opposite. Too many people I guess couldn't handle the left turn on yellow.
It's hard to argue with a perfectly reasonable, perfectly safe driver.