“Explain”, “Is that a thing?”...
(Sigh) See what I mean?
Okay.
On a multi lane highway the leftmost lane is reserved for passing vehicles.
The lane is used for quick and active passing and is then reopened by shifting right after the pass as much as traffic allows.
If one is approaching at speed and sees that a slower vehicle is either shifting left to pass with their faster car bearing down, or a car is occupying the passing lane with no traffic to it’s right a driver might flash the car’s brights assuming that the driver has temporarily lost a sense of their position and the current situation.
If I happen to be in a left lane and observe a driver shifting left for no reason I would likely flash my brights to let this driver know that I’m closing fast and the driver has made a needless mistake.
At any given time a driver should be as far to the right as the situation allows. This opens all lanes to the left to quicker traffic.
Driving is a full time occupation. One duty of observation and reaction is constantly overlapping another.
There is no time or mental capacity left over for a driver engage in any other activity.
Make your phone calls and eat your lunch at home or the office.
Like I said above part of your car payment is going toward paying for those rearview mirrors, you had might as well use them. Check your fucking 6.
If a car behind you is flashing it’s brights especially with the left signal on the message is clear: you are needlessly clogging the passing lane.