I have 2 in-person stories of Cruise cars on the road in SF.
The first: the San Francisco Muni bus I was riding on almost ran over a Cruise car at an intersection. The intersection is a complicated one - there are 5 passages out of it, none of which are 90 degrees to any other. We all started at a red light. The Cruise car in front was apparently choosing to turn to the 2nd left, with the bus I was riding on behind it. The Cruise car turned - all seemed fine until it slammed on its brakes about 2/3rds of the way through the intersection. There were no other cars in front or beside it. There was no obstruction. The bus wasn't moving that fast, but wasn't moving that slow either (it is an electrical trolley bus).
The second: I had rented a car to go to a meeting 50 miles away. Since I had the car, I went to the grocery store since I had time before the meeting. When exiting the grocery store parking lot - which is a pain because cars parked along the road, due to the slope, block vision for incoming traffic coming from the left.
I pulled forward a bit, nearly to the roadway, in order to see. A Cruise car is coming along. It turns on its right turn signal like it is about to enter the grocery store parking lot. I wait, because human drivers are not trustworthy - fortunately because the Cruise car not only didn't turn, it accelerated and edged closer to its right to almost hit me.
Note both of these aren't even the normal heavy traffic, pedestrians staring at cell phone, dogs and homeless people meandering across the street, giant pothole, flying trash, Uber/Lyft car stopped anywhere types of city SF driving situations.