Here is an unknown car - you think it could be filled with bad people.
So, instead of just calling the law - you go out (in many variants) and expose yourself to them.
They ARE bad people and they shoot you or beat you up or stab you (of course, you
can handle it).
Why is this continuing?
Or they are innocents and they call the cops on you. Man with a gun (for instance). Not a man engaging in open carry lawfully - but man with a gun - for a fun night time adventure.
Turn on the lights and call the cops, if you truly expect a threat and it isn't two kids necking.
My wife and I were returning from the park (our neighborhood hooks into a neat trail system). In the far reaches of the parking lot, we heard cries and moans. Thus, I took out my Surefire and Glock 19 and crawled to the car, jumped up and yelled - I'm from the Internet.
Or, we looked at each other, smiled and remembered our youth.