One boundary is responsibility. Personal responsibility focuses on individual feelings, motives, wants, goals. Driving is also decision making. People are authors of their own behavior and are often labeled speeders, drinking drivers, risk takers. Drivers adjust their behaviors according to the responsibility they share to maintain patterns of joint action.
Legal responsibility is like a social contract between drivers and the state.
It's expected, if the driver chooses irresponsible driving, they should accept expected costs of an accident or change to an alternative conduct. Fault may be considered part of normal behavior or it may be a momentary act of inattention or distraction. Traffic safety may not lie in foolishness of drunk driver, but the failure of auto industry to construct an automobile assuming they will be foolish or drunk and not construct the vehicle as so. Intention doesn't negate legal responsibility, it modifies it. Ignorance of law is not reasonable justification for negating driver responsibility.