> he said "you may have the right of way, but you'll still be dead if one hits you"

  Here lies the body
    Of William Jay,
  Who died maintaining
    His right of way.
  He was in the right
    As he sped along,
  But he’s just as dead
    As if he’d been wrong.

Edgar A. Guest, possibly. Some variations and discussion here:

https://literature.stackexchange.com/questions/18230

This kind of is Postel's law, in a way:

https://en.wikipedia.org/wiki/Robustness_principle

Re 1: Goethes Zauberlehrling might fit

Your dad was a wise man.

In my country there is a saying: "Graveyards are full of pedestrians that had the right of way".

This almost sounds like The Monkey's Paw by Jacobs.

How about the sorcerer's apprentice?