There are only a few miles of freeway in the entire city of San Francisco, so I doubt too many of the accidents in SF are from them. Yes, driving 25mph in a modern car with crumple zones and 10 airbags is generally very safe. If you look at the statistics [1], most traffic fatalities in the city are either pedestrians or bicycles. Avoiding pedestrians and bicycles is one of the tougher challenges of making a safe AV, and San Francisco is one of the most challenging places in the country for this.

[1] https://sfgov.org/scorecards/transportation/traffic-fataliti...