They both do it promptly, lest the other one beat them into it. They both do it quickly, instinctively, almost aggressively. They both signal others. Yet they couldn’t mean more different.
One is a driver in American road flashing his headlights to yield right of way. He is more than willing to wait patiently while you go ahead and he voluntarily signals permission. Other is, in contrast, a driver on Indian road flashing his headlights to demand right of way. It’s unofficial rule of Indian highways: first flasher gets right of way and coming vehicle must yield. Hurry to be first often leads to flashing as early as when distance between vehicles is more than 300 meters. He doesn’t do it only where there is only single lane for both sides, he does it then too when he is overtaking by coming in your lane. That it’s your lane be damned, since he flashed first, he has right. Funny, and dangerous, part is that he assumes that flashing is enough to carve way for him and whether you have sufficient time or place to yield is not his problem. So even when he is directly ahead you within 20 meters, he will flash, and you better get off the road however before he hurls at you. If you follow local news on Indian roads, you will notice that maximum number of road accidents happen because of aggressive overtaking.
Why are we so (stupidly) hurried on road? Have you seen how auto-rickshaws and two-wheelers seek niches and corners at traffic crossing to advance few inches even when traffic light is red (four-wheelers would do it too if they could)? What do they gain by gaining few inches on road? How much time will it save them in their journey? It seems any advantage in moving forward now is more than nullified by having to reduce speed when light turns green because, obviously, final speed is determined by vehicle in front*. So if I have three feet free in front of me at signal, I am not really losing anything. Same shortage of common sense leads to mass honking when signal turns green. Working on the sensible premise that no one likes to stay parked on middle of road, and hence when he is stopped he must have a genuine reason such as vehicle ahead of him or some obstruction, and that honking cannot really get rid of reason concerned, what exactly is point of honking?
Our need to hurry without reason or advantage to hurrying is so great that passengers block the passageway and obstruct foot traffic on the aisle of train compartments and bus by arranging their luggage as much as an hour before arrival of destination station. Why? So that when train or bus stops, they can instantaneously disembark. By preparing and inconveniencing themselves and others for more than a hour, they gain a minute on arrival. I am sure it must matter a lot in their life. Such ridiculous behaviour has been observed even in airplanes when Indian national tendency warrants passenger to pick up their luggage and gather around airplane gate as soon as plane lands on the runway and is still taxing to the gate with seatbelt sign on. After all, in most cases your arrival to airport lounge is decided by departure of bus which picks you from the airplane and not by speed of your disembarkation. Keeping principle of bottleneck in mind is usually a good idea in life in these cases.
(This post is based on experience from a lot of driving around in last four months.)
*When I was little I used to think that when my school bus got stuck in traffic, I can speed up my arrival to school by getting off, walking ahead of bus, and getting on the bus again when it catches up to me. What happens there is a lot like this.