To not be legally "at fault" is important, particularly for a company with liability and public image at stake.

I genuinely look forward to future stats that will tell us self-driven cars have a much lower likelihood of even being involved in accidents, independent of fault. To me, that level of defensiveness and net safety is also a measure of progress.

As an example: Let's say a particular self-driven car has a low threshold to "stomp on the brakes, hard" at the slightest sign of danger. Will this keep it from accumulating "at fault" accidents? Probably. But can that behaviour effectively contribute to causing accidents that it's not "at fault" for (being rear-ended)? Probably. Safer roads? Difficult to say.