I suppose there should be a difference in civil vs. criminal but traffic accidents are not always purely civil matters. If the accident is caused by a violation of a traffic law shouldn't that be considered criminal. At least in cases where intent to harm or accidental death, criminal charges are sometimes pursued.

Regardless, I don't think liability should be a default in any case. Let the circumstances of each accident decide who is responsible. If there is a clear guilty party and a clear innocent party, why should liability be handed by default (possibly to the innocent party)? Is it not an injustice for a victim to take responsibility for the actions of the transgressor?