People have to drive. That’s the way cities in North America are made, and I suspect the same applies in a lot of other countries.
There are people that enjoy driving, but when it becomes something you have to do in order to get chores done, it’s understandable if it’s not fun anymore.
These two points above make some kind of case for why I would say most people driving don’t actually want to be driving most of the time.
Now, we also have annoyances while driving. There is a street light I often have to wait at which will give me an eternal red light even when there is no traffic. There are a lot of cyclists here that want to be treated like cars, but don’t want to show the same considerations to cars. Basically, driving can be aggravating, and people may form bad habits in response: such as driving very close to cyclists to pass them without going into oncoming traffic, or racing to beat a red light at all costs.
In conclusion, I think a lot of people don’t really want to be driving, don’t stay mentally engaged while driving, and will act like assholes while driving because they expect other people to do the same to them and the driving experience is frustrating.