A lot of car fatalities are accidents that don't involve alcohol - around 70%.

One time I lost control of my car while driving on the highway and hitting a patch of black ice. Luckily, nobody died. But that happens all the time.

Presumably, a self-driving car will drive slower in adverse weather than a human might, as well as being able to control the car if it hits an ice patch better than an untrained human can.

Also, the car can notify other cars on the same road of the ice patch, instantaneously.

And to be clear, this largely makes sense: humans are not good at preventing long tail failures that require constant vigilance and are not responsive to unlikely punishments, no matter how severe. The thing we have to do is improve the systems in which people operate.