Generally, I believe that everyone is good in nature, but under certain circumstances they turn bad, apathetic, desensitized, impolite, and uncaring.
I've come to this conclusion because of the change that I notice in myself. We all start the day off, for the most part, with a normal level of courtesy and politeness, but as our day goes on, the irritants build.
The overcrowding of the city and commuters add to the problem.
For those who drive to work, aside from stressors at home, have to deal with traffic jams and idiot drivers. Every time one of these events occurs, it alters your mood, making you angry, and upset before you even get to work.
For those who take public transportation, you are sardined into a small space with hundreds of other people, just getting to the bus or train can be a hassle, getting around the people that don't care they are blocking the way for people trying to get on or off the bus/train. Then you have to deal with the people in a confined space, the gum snappers, the people putting their bag on the seat next to them and not letting people sit down, despite the fact there are at least 12 people standing. The smelly homeless person riding, that makes you get off and take the next vehicle, just because you can't stand the smell. The person who slops their coffee on you, because they are too busy reading the paper and eating a donut. The person yapping on the phone, practically yelling, thinking that the lower the signal strength they have, the louder they need to be to be heard. The people that, probably by no fault of their own having been irritated longer than you have that day, shove you to one side, without saying, 'Excuse me' so they can move by you.
Reverse commuters have it even worse on public transportation. I walk against a wall of people, eight wide, just to get to the train station in the morning and routinely have to step down onto the street, because they will not give me room to walk on the sidewalk. Then, when there is no room to get out of the way, people not paying attention to where they are walking, ram into you, and it's your fault that you were in the way, or they hit you in the leg with one of those bags with the wheels, and it tips over and they get pissed, because you knocked it over.
The lack of courtesy and taking thing for granted really gets to me, so, I get to work and I a m already in a pissy mood, so I do my best to calm down, thank goodness for cig breaks. ;)
Then I go through the people all over again trying to get home, only it's worse, because everyone is in such a hurry to get home, they could care less about you.
People being frustrated by little things, add up, and now, it's rare to see people being polite, courteous, or using common sense, I feel like a salmon swimming up stream, with bears swatting at me.
Because we all have to deal with more and more callous people, it in turn makes us more insensitive to others. At least, I recognize this and am doing the best I can, to not turn into the people that annoy me the most.