Indians, as I see it, are either completely ignorant of or display no regard for public etiquette.
The most glaring example of this is the number of people you will find yelling into their cell phones in public places. On buses and trains, on the sidewalk, in parks, in restaurants etc. Okay fine, the cell phone was invented in order to give you a mobile connection and so refraining from using it in the above places would probably defeat that purpose; but do you have to yell? Is everyone in India deaf?
Audiences in movie halls rarely switch off their cell phones, and often don't even switch them to the 'silent' mode. Hence movies are frequently punctuated with the ringing of a cell phone, most often the tone being a tune from the latest Bollywood blockbuster. And this is followed by a conversation that will be loud enough for the entire row [if not the entire hall] to hear. If you must receive calls during a movie, how hard is it for you to step outside and do so?
Indian men stare a lot. At anyone belonging to the opposite sex, regardless of age, dress or physical features. No woman can walk on the street in an Indian city without attracting at least some stares. And most would be fortunate if staring was all that they had to contend with. Unwanted hands in inappropriate places and muttered profanities are not uncommon on buses or in crowded streets.
As far as the traffic situation is concerned, drivers will not display the least bit of concern for either other drivers or even pedestrians. Drivers will cut into traffic right in front of you, stop and park in the middle of the street, and switch lanes with gay abandon. The most irritating habit, though, would have to be the Indian driver's use [or rather abuse] of the horn. Most drivers use the horn in a manner not unlike how a race car driver might use the gas pedal - keep it pressed, often and hard! One might be forgiven for believing that the horn was responsible for producing acceleration and transporting the vehicle from place A to place B. Some drivers even try to compose a tune with it, as they swerve in and out of traffic. And God forbid traffic should not start moving as soon as the light turns green at an intersection! All the drivers will then immediately launch in a cacophonous orchestra of horns, rising in crescendo almost as if guided by an unseen conductor.
Pedestrians, for their part, offer the same insolence to vehicular traffic as they receive from them, often walking down the middle of the street instead of on the sidewalk. However, in a country where the only traffic rule is "might is right", they are ultimately forced to conform to the whims of the drivers.
Of course, not all Indians behave in this manner. But there are too many of them who do.