You can normalize the report by miles driven, but if the number of miles driven by those services increases rapidly then you can expect the number of incidents to increase just as rapidly, and that is what appears to be happening. There is a level at which this becomes untenable and that level is a direct function of the number of miles driven.
So unless you see some kind of cap to the number of miles driven (which given the ambition to scale up is not something I would subscribe to) I believe this is an early indication of something that may well develop into an actual problem in a relatively short amount of time.
I think this is not taking the analysis far enough. You need to compare incidents per passenger mile, with humans vs. AV.
If AVs are safer, and you increase the AV miles driven, presumably you mostly displace human miles driven (e.g. Uber). In this possible word you would see the missing graph of human-driven harm go down, but you’d still see the graph from the OP go up. Indeed in this scenario the more the AV mischief goes up, the better, as that would be implying that there are fewer humans on the road. (Obviously it’s not only displacement but I think that’s the first-order effect.)
Without quantifying the level of human-related mischief, I don’t think it’s wise to draw strong conclusions.
So unless you see some kind of cap to the number of miles driven (which given the ambition to scale up is not something I would subscribe to) I believe this is an early indication of something that may well develop into an actual problem in a relatively short amount of time.