>in my experience, the Cruise cars are very hesitant to make left turns

I'm sure unprotected (i.e. no arrow) left hand turns remain one of the more difficult routine scenarios to fine tune. What works in (I assume) Chandler Arizona and San Francisco are probably two very different things. A large busy city like San Francisco simply requires a degree of aggression--Pittsburgh lefts, cutting through fairly small gaps, etc.--that would be inappropriate in a calmer and less busy environment.

Well one failure was at 19th and Mission where left turns are illegal, another was at 13th and Folsom which I think is a protected turn, another was on 11th street where the drivers decided to make an illegal u-turn.