Yes, that's a pretty common counterargument. Having a large number of autonomous cars roaming the streets during the day like zombies isn't really sustainable.

Yes, that's a pretty common counterargument. Having a large number of autonomous cars roaming the streets during the day like zombies isn't really sustainable. But, with companies like Tesla promoting the idea that you car could be productive via ride sharing during the day, it might prevent the cars from at least wandering aimlessly. Fortunately, many self-driving car companies are using alternative fuel vehicles (Cruise uses the Bolt, Tesla is obviously electric, Waymo has the i-Pace and Pacifica Hybrids), and things like inductive charging are also helpful for complete autonomy so the future of autonomous zombie cars may involve fewer tailpipe emissions at least :)