There is typically a fine for parking your car on the street facing the wrong direction, i.e. against traffic. What is the harm in that?
Economic theory suggests that penalties should be attached to behaviors that are correlated with crime and not necessarily to criminal behavior itself. For example, price fixing may be impossible to detect, but conspiracy to fix prices may be much easier. It makes sense to make cheap talk a crime even though the talk itself causes no harm.
When you car is parked facing the wrong way its a sure sign that A) you previously committed the crime of driving the wrong way and B) you will soon do it again.