Comment by simoncion

> PSA: Flashing someone is never a signal that you're giving them priority.

Uh. I guess you've not many US highway miles under your belt. If nothing else, it's a very common nighttime signal to let passing truckers know that they've room to get back in the rightmost lane. I can't imagine that the signalling situation is much different in other places that have a large population of generally-decently-skilled drivers.

> If someone flashes you, you should make your own determination whether it is safe to perform a manoeuvre...

Sure. The operator of a vehicle is ultimately the person who's responsible for its safe operation.

Having said that, few drivers are interested in killing their fellow travelers. Especially at night, determining the "time of arrival" of oncoming traffic, or the distance between the end of your bigass trailer and traffic behind you can be quite difficult. If it's customary in your area to use headlight flashing to indicate to traffic ahead of you that it's safe for them to perform whatever maneuver that they may be uncertain about, then it's not unreasonable to assume that the driver that uses that signal isn't attempting to kill you with misinformation.

Automatic high-beam-togglers don't really care about anything, [0] so that's definitely one piece of malfunctioning tech that makes the roads less safe.

[0] ...yet!