I may have posted this before, but there was a case in the UK some years ago involving a spate of accidents at a certain junction. Cars were going straight across a STOP line and being hit by main road traffic which had priority.
Blame was easy to determine, but a traffic engineer decided it was more important to find the cause. He took the view that these collisions were 'accidents' in the sense that they weren't intended. The police were asked to monitor the junction for drivers failing to stop but not to issue tickets, instead to ask the drivers why they didn't stop. The local 'someone is always to blame' brigade got irate at the lack of prosecutions, but not before the police had learnt that the Stop line was very difficult to see in certain lighting conditions. The line was repainted a few feet further back and the junction became much safer.
Quite frankly I'm prepared to go without apportioning blame if the cause of the accident (and yes there are such things) can be determined. The AAIB generally behaves the way the traffic expert did in this case, and rightly.