deco13

@FirestarteR93 Flashing your lights is allowed in many situations and not allowed in other situations. For example, you can get fined for flashing your lights to alert drivers of mobile speed cameras but you can flash your lights to notify a driver that they can pull out of a junction.

Ok, this is obvious, maybe it's a question too general XD 

I meant, in the situation when there are only two drivers (no accidents, no other cars/trucks, no danger in general), one has overtaken and the other has been overtaken, so, the driver that has been overtaken does NOT doing nothing to let understand that who has overtake can go through, he is completely passive. What does the hazard means in that situation?

I would put hazard lights on to remind some trucks if they have dropped their loads on freeway, or have a flat tire or broken light or other things that drivers cannot see in the cabin.... These can happen at times.