> I think it's reasonable to say "we have done enough" at some point though. We can debate where the point is, but safety is not an unalloyed good. It has a cost, and reasonable people can disagree over whether a particular safety invention has enough ROI to justify its existence.

That has to be a point in time decision though. Closed circuit TV backup cameras in cars have been possible since I dunno, probably the 70s, certainly 80s technology could have done it; but they weren't a reasonable intervention (outside of say armored cars for currency transports) until more recently as cameras and displays have gotten less expensive and quality has improved. Also helpful as modern vehicle design has resulted in significantly reduced visibility compared to the past, but that's a rant for a car article :P