There is such an incredible shortage of common sense about the practicalities of driving, as well as so many people who seem unable to think clearly any more. You cannot get people to drive better just by saying "drive better". I think the problem of poor driving habits and some of the emotional and health issues (fatigue, stress, aggression, time shortage) behind bad driving are more a social problem.
This reader's observations are something that I have often commented on. Many drivers seem to be saying "I'm important, you are not. I'm in a hurry, get out of my way" when they are behind the wheel. Hiding in their steel cocoon, they are anonymous and to some extent is everyone else present on the highway. Perhaps because we don't know each other and probably won't ever meet face to face, we don't have to extend social courtesies to each other.
Other drivers like you when you conform to their concept of proper driving, whether they are correct about what is proper or not. Witness a long line of cars that have merged into one lane well before an adjacent lane is closed due to construction. There is nothing unlawful with using the lane that is going to be closed until the point where it is actually closed. Try it. Drivers will move to block you, open their doors to prevent you passing and wave in a very unfriendly manner. They are waiting, you should too, another social faux pas.
How do we change the social outlook of a driver? As a police officer I had only education and enforcement to use in conjunction with the Ministry of Transportation's engineering solutions. It was not a simple task and I often wondered if I was making a difference at all. I hope so.