This kind of behavior is happening (and its not just in driving; its in all our activities) because the majority of people in this country have become self-centered, lack what used to be called common courtesy, are convinced that they and their interests take precedence over everyone else and their interests, and are unconcerned about the lives, interests, and safety of others. Its all me, me, me, and to h... with everyone else. You can also see this in the constant demand for people that their rights be recognized -- the right to this, the right to that, the right to the most asinine things, ad infinitum and ad nauseum. At the same time, they ignore the responsibilities that go along with those rights. They aren't willing to be responsible for anything. It has long been recognized by political theorists that rights are balanced by and accompanied by responsibilities. As stated in Article II, section 3, of the Constitution of the State of Montana:
"Section 3. Inalienable rights. All persons are born free and have certain inalienable rights. They include the right to a clean and healthful environment and the rights of pursuing life's basic necessities, enjoying and defending their lives and liberties, acquiring, possessing and protecting property, and seeking their safety, health and happiness in all lawful ways. In enjoying these rights, all persons recognize corresponding responsibilities."
Note the last sentence.
You also see this reflected in the proliferation of commercials that say "You deserve it". We're told that we deserve this, that, and the other thing, tho often many people don't deserve it, for the simple reason that they didn't earn what they're told that they deserve. My favorite is the people with lousy credit ratings that are purely their own fault because they have steak tastes on a hamburger budget and buy, buy, buy, and are then told by the commercials that they deserve the credit card, product, or whatever, that the commercial seeks to sell them.
I grew up in the 50's. I was in college throughout most of the 60's. The difference in people's interactions with each other and how they treated each other in those two decades is the difference between night and day. It was in the 60's that this self-centeredness began. I realize that a lot of good occurred in the 60's, and that a lot of necessary and positive changes were made, but I've come to believe that on the whole, the 60's were a disaster for the future of this country and it would have been better for us if the 60's had been more like a continuation of the 50's.