Sure, if the complaint rate per mile is constant, but the number of driverless cars increases exponentially, then yeah we might expect the number of complaints to increase exponentially. That doesn't mean this isn't a problem.
they say it's "incomplete"
Okay, so maybe there are more problems than are represented in the chart, but that doesn't seem to paint any prettier of a picture here.
So, by your logic, the public policy we should be looking at is reducing human diven car miles to a minimum.
If you ignore the rate at which the events are occuring and don't bother to collect any data on the relative rates of other things like standard taxis and delivery vehicles, then your "data" is worthless from a public policy perspective.