Why people drive like this?

The road in topic is Hosur Road between Silk board junction and Electronics City. Some of the highlights are: Fly-over construction is under way and lots of people cross this road from both ends and it is more near Bommanahalli and other few points. This road has become kind of 4 lanes, each of 2 lanes for one way traffic.
Let me now come to the core issue of the topic. I’ve seen people driving on this road. Let me describe this in detail:

Two-wheelers: They are also one of the craziest drivers. They try to squeeze in wherever possible. They are also not bothered about the lane. They keep switching the lanes. The way they drive the vehicle is like a dirt track race.

Cab Drivers: All cab drivers including private maxi-cab drivers come under this category. They are worst. They drive as if world is going to end today! Still worse they just don’t bother about fellow drivers. When they are switching the lanes, they don’t even bother of looking at the rear window and they assume that whoever is coming from the back at the other lane should stop. They are also one of the top contenders in “Most Honking” category.

Heavy Vehicle Drivers: Bus and lorry drivers come under this category. The driving by private bus drivers is most horrifying. The way they make their own way is very dangerous. Sometimes I think of dragging them out and hitting! Another common scene is the race between private buses! They have made this road a race track. They keep honking as if it is an ambulance!

Why drivers don’t understand that it is dangerous to drive zig-zag?
Why drivers do not care to follow single lane?
Why drivers do not have patience to wait for pedestrians to cross the road?
Why drivers keep honking despite knowing that traffic is moving slowly?
Why drivers do not implement basic driving rules?

Why?...