If your goal is to assign blame, it can never be done on such a naive scale. The US has very well written liability laws, e.g. for Q2 every party involved assum

If your goal is to assign blame, it can never be done on such a naive scale. The US has very well written liability laws, e.g. for Q2 every party involved assumes some liability. For every car crash, the individual assume some liability (that's why we all carry insurance), car companies assume some of it, parts suppliers do (remember the Ford/Firestone issue where the explorers were flipping over?), USDOT (e.g. CalTrans in California) does and the regulators at NHTSA do. There is a reason why legal and insurances industries are so advanced. Blame is never black/white.