[SixSigma]

> If guilt can't be proven for sufficiently to assess which driver's insurance should pay for the costs of an accident, how can guilt be proven for the much stricter requirements needed for manslaughter?

Guilt could be proven for more cases but the cost is prohibitive. It is cheaper for all concerned to just say "we know what happened, let's not bother finding out how and just split the costs of repair", the drivers pay higher premiums for a while, they probably share the blame anyway and both will drive more carefully from now on.

When one of the parties could go to prison for life, society decides to accept the burden and does a full investigation.