Well, I posted this on advrider and the inmates said flashing your headlight might signal the driver to go ahead and cut across in front of you. It seems like only a special breed of idiotic driver would do that, but they’re probably out there.
To help visibility it is instead recommended to weave your bike if you can safely do it.
Also, prepare to ghost ride if someone pulls out in front of you and there is no room to brake or turn.
Rides: KLR650, KX250