I'm very interested in these kinds of stats. I'd imagine this is like any other distribution - long, long tailed; with lots of drivers who have driven once, twice, or what have you. Give me the stats on heavy drivers. What fraction of drivers work > 40 hours a week? What fraction of miles driven are driven by heavy drivers? What fraction of <10 hour a week drivers have other jobs? How many hours a week does an Uber driver without another job drive on average?
The company is giving us just the slice that looks good. I'm sure if you started diving into these questions, it wouldn't be pretty.