Organized chaos is the best term I could come up with for what happens on Indian roads. Millions of vehicles, people and animals, all using the streets at the same time. There is a hierarchy of importance loosely based on size, with the exception of cows. People move out of the way of bicycles, bicycles move out of the way of scooters. This continues upwards through auto-rickshaw, compact car, full-size car, SUV, light-truck and bus, to dump truck. Cows are the anomaly, as even dump trucks stop if these sacred animals are crossing the street. Very few vehicles have side mirrors, so you are expected (and in some areas obliged) to beep your horn while overtaking. As everyone is in a rush, the beeping is incessant.
Accidents are very common, but not as often as I you’d expect (possibly due to the slow speed of traffic). You certainly learn to never make any assumptions. When driving on a 6-lane highway with a central divider, don’t assume that the vehicle in the inside lane is the fastest, don’t assume it’s going in the same direction as you. Don’t even assume it’s a car at all. Why did the chicken cross the road? It was following the elephant, cow, camel, monkey, pig, dog, cat and horse.
I didn’t see any major crashes while in India, but there were plenty of totaled vehicles strewn beside the roads. I was told crash helmets were mandatory in the major cities, but in most places, the motorcyclists rode as if there were no tomorrow. For some, this would be all too true.