I'd say that miles driven is a good normalizer.

In fact, NHTSA statistics includes miles driven under adverse conditions (rain, snow, etc) while I'd bet that this is not the case for Uber.

Statistically, I don't think that miles driven on lonely freeways equal those in Manhatten. And perceptually, running down city pedestrians at 40 MPH will impact public thinking more than highway fatalities.

True.