I don't know why that matters? The city selection and routing is a part of the overall autonomous system. People get to where they need to be with fewer deaths and injuries, and that's what matters. I suppose you could normalize to "useful miles driven" to account for longer, safer routes, but even then the statistics are overwhelmingly clear that Waymo is at least an order of safer than human drivers, so a small tweak like that is barely going to matter.