Yep, this is the thing that worries me the most on some of these systems right now. They are going to get rear-ended a lot for the next few years, IMO.
Rear ends have basically no fatality rate though. They do have material costs but if optimizing for no loss of human life it sounds more appealing.
These kind of tradeoffs were things every self-driving car software developer KNEW they were going to have to deal with - the most extreme being the one where the software has to decide who to kill and who to save: