> Toyota couldn't get the software for an accelerator pedal right, so I have zero confidence that the 2030 self-driving Prius won't just e.g. drive 15 mph under the speed limit everywhere, camp out in the passing lane, stop for at least 30 seconds when switching from reverse to forward, and gridlock in shopping center parking lots.

All the things you describe are as likely to cause accidents as wrong turns or over-acceleration. If Toyota can't get this right (my bet is they will) then they won't and shouldn't be doing autonomous cars, despite their "change of heart".