Yeah you see some scary driving in India. But most of the time we can't look at it with a western way of thinking about driving. Believe it or not, there's a system to that madness and they kind of know what they're doing. And sometimes even if we think all we can hear is tooting horns and mess, every one of those horns is doing a specific job. Hard to describe, but I guess it kind of works over there.
Still, some people do cross the line every now and then and it can get very scary. Picture a fast highway with four lanes, two going each way. What to do when you're already in the overtaking lane and you want to pass the guy in front of you? Well, since there's no barrier in the middle, you can use the third lane, which happens to be the fast lane in the opposite direction! Now, that can get veeeeery scary!!
It's like that in Viet Nam too. Drivers honk to let others know that they are there. It's not considered impolite to honk.
+1 that's right. And many vehicles actually have "please honk" written on the back of them.