During a sermon preached in the church in which I grew up, the pastor mused about the nature of time. Among other things, he noted that "the shortest interval is between the time the light changes green and when the car behind you honks at you."
I often feel that I am an oddity in Southern California, in that I don't use my horn very much. Certainly, I'm glad it's there. It is an important safety feature of a car. If someone in front of me appears to not be paying attention to the task of driving, I think it's perfectly appropriate to use the horn to "wake them up," for example.
But most of the time, it seems to me that people use their horn to express anger or impatience, and I don't think this is so appropriate. For example, when driving down a heavily trafficked lane, a car clearly wanted to turn left from the opposing lane into the restaurant immediately to my right. Traffic was backed up enough that, if I had driven to the back of the car in front of me, I would have effectively blocked the turning car from being able to get into the restaurant. So I slowed down and stopped so that the car could complete it's turn. While the car was still in front of me, the car behind me honked. How rude! Does this person expect me to plow straight through the turning vehicle? I find the same thing happens often at turns where pedestrians are trying to cross. Any car who is patient enough not to cut the pedestrian off is rewarded with angry horns from other drivers.
And it's usually not a simple "honk," either, but a long, loud, sitting-on-the-horn kind of sound that, so far as I can tell, serves no practical purpose whatsoever except to serve as a vent for the driver's anger and frustration. This is not the purpose for which the car horn was invented.
I don't claim perfection in my driving, nor in my ability to remain patient when other people are walking/driving/etc too slowly for my convenience. I'd rather be spending my time at whatever destination I'm driving to, rather than doing the task of driving itself. All I really can do is try to be polite myself (and it is an effort sometimes!), and hope that other drivers will pass the favor on to others. I know that people appreciate it when I make the effort to be polite, often because I see a grateful wave "thank you" in response. I have no idea if they remember when a situation might call for them to respond in kind to another driver or pedestrian, but I like to think that, maybe, the culture of anger that seems to permeate Southern California drivers can be turned around.