Add to this list, the drivers of the Govt. City buses (here in Chennai). They would stop right dead in the middle of the road at the bus stops instead of moving to the left and stopping near the kerb. Even if the you see the bus by the kerb and then you start thinking, "Oh! This driver is good man!"; and the moment you're about to pass him, there comes the knockout punch that to too, below the belt. He would just swerve into the right (that's supposed to be your lane) without any signals and giving you nightmares.
Especially during the slow moving traffic, these bus drivers (due to their height advantage and non-insured status) would squeeze you out of your lane.
And we have got "share autos" too. Though they help in people travel a bit more conveniently than the public buses (cost wise also cheaper than the hired autos), for a fellow driver aka vehicle owner aka car owner on the road, these are nightmares too. You never know where he will pullover or cut your lane from the left.
Parking menace: Right in front of the gates.
Zebra crossing: If I yield to the pedestrians, the auto or bike guys take up that space
Yielding at the intersection: a) Fellow drivers behind you think that you're a stupid. They express this concern by honking their horns.
b) If you forget to go bumper to bumper, then a bike or auto from the other (left or right) intersecting road will make you to stop.
Coming back to the why part of it, as someone here has already mentioned that we're programmed as such. Yes! I'm sure most of you would have also seen/experienced this attitude; that is "standing in queue"; or let me put it this way, "not standing in queue". Especially outside the ATMs, if 3 or 4 people are standing in queue, the new person would come and stand in front of the door instead of joining the line. He/she would just keep the count mentally and tell you,"Sir! I know sir that I'm after the 4th person". We've learnt/borrowed a lot of social concepts from the western world. I always wonder why our society can't just respect a queue
Illiterate or literate, poor or rich, young or old doesn't matter. We've forgotten the fact the our society has a VALUE.
P.S:
"pom, pom, pom..... (that stupid musical horn thing with cut-out relay)" and the driver yells at the pedestrian,"I'm honking the horn na? Why can't you give way (or move aside)?"
//You stupid f***tard,"There is also a thing called brake in your vehicle; why can't you use it also?"//