So... when there is somebody who isn't a Parisian and they hit a car because they did not know this, are they in fault?

I live in Paris, and although I do not drive I have the impression that most drivers here are extremely inconsiderate. As an example, there is a crossing which is constantly congested with buses and lorries stuck in the middle here. This is mainly because nobody respects the rules or priorities. When an officer comes in to control the traffic instead of the lights, it gets "magically" cleaned up and the circulation is fluid.