[crazygringo]

Because accidents are rare and drivers are expensive so that might be the world's most expensive study to get to a statistically meaningful number.

It's easy enough to simply compare with existing Uber in the same city along the same roads and get something nearly as accurate for virtually none of the cost.

[scott00]

Drivers doing nothing productive are expensive, but drivers working ride hail are somewhere in the range of cheap to slightly profitable.

The comparison with Uber depends strongly on how similar the dispatch profiles are, and I would not be quick to assume that they are similar. If they are limiting the self-driving cars due to weather, or time of day, or any property of trip type it could easily have a substantial impact.