The goal is not to achieve perfection, just demonstrably more safe than an average driver.
I'm curious how we will evaluate average driver. Clearly, including drunk driving accidents in the mix is not a helpful metric for safety-conscious drivers.
Sure it is. Even if you never drive drunk, there are still other drunk drivers on the road who are a danger to you.
But a self-driving AI, even an imperfect one, never drives drunk.
Who among us would admit, "yes, I am a bad driver, I need this more expensive thing to take control in the event of an accident"? Very few is my guess. In 2019, people use these for convenience, not because they think the system is a better driver. I bet that's true even for Waymo's taxis.
As for getting drunk drivers to use self-driving, that's as easy as asking them to either stop drinking or not drive. Then there is the cost. I wouldn't be surprised if the unemployed drink and drive more often.
Cost is definitely an issue, but reducing accidents and increasing convenience have a cash value which could pay for it if the research pans out.
What social factors do you have in mind?
It seems unlikely that people who buy/use early self-driving cars have the same percentage of drunk driving as the general population. Surely employment rates would be a factor, for example.
But even if it is true that those who drive cheaper, older cars are more likely to drive drunk? Today's new cars with high-tech self driving features are tomorrow's affordable used cars. You have to start somewhere.
In practice, the target seems to be not just the average driver, but the best human driver (or at least the 99%th percentile.) Given the trajectory of improvement we often see with AI, surpassing the average human and surpassing all humans shouldn't be too far apart.