Earlier quoted context omitted.
also, human failure modes are better understood, and can be better anticipated by e.g. you can still have a somewhat predictive mental model of how a swerving drunk drive might behave. We don't have a good frame of reference for how machines might behave with their failures, which means that accidents could be worse than they would be otherwise.
The severity of the accident is an interesting point. Though it intuitively feels like there are ways for software to mitigate the severity of an accident when it realizes it is about to crash than a human who might be asleep, intoxicated or otherwise have a slower reaction time.
A human driver is somewhat likely to eventually realize what situation they've gotten themselves into (oh no, i can't stop in time) because of the multiple different feedback loops and information sources they're working with combined with their experience as a driver. For example, a drunk or very tired driver is operating with impaired decision making and response time, but they may eventually notice and respond - while an AI misclassifying a fire truck as a stop sign may very well continue misclassifying it until impact.
One way to mitigate this would be via sensor fusion - even if your vision or radar sensing fail, you can rely on data from other sensors to do things like apply emergency braking.
Unfortunately at least one vendor has decided to ditch radar, lidar, etc and just go with vision!