How to explain "road rage"? How is it possible that (otherwise normal) people who are "just driving" can be overcome by such overpowering, unaccountable impulses?
A consumer culture (such as ours) promises so much that it is not surprising when those promises are not honored.
When Detergent X promises to make our whites "whiter", and our colors "brighter", we may not notice any changes in our clothes. But, subconsciously, we remember The Promise.
Now consider the Promises which automobile advertising has consistently offered throughout our lifetimes: empty roads, unlimited speeds, perfect comfort, absolute safety for our children, and a satisfied integration between Man and Machine.
Every day, you can hear the moist, profound "thunk" when these long advertised expectations hit the experience of Real World Driving.
This would be one explanation for the emotional volatility of Motorists.
As an occasional Motorist myself, I can think of another reason - more related to the basics of Human Nature.
As they seal themselves into their cars Motorists have a certain Expectation of how long their prospective trip should take. In CLUELESS, when Dan Hedaya says "Everywhere in Los Angeles is 20 minutes away from everywhere else...." he is expressing a typical Motorist mindset.
When the car's engine starts ... so does the Internal Clock.
And, as has been chronicled in this forum repeatedly, delay ... or the prospect of delay ... or the prospect of the prospect of delay, opens the floodgates of adrenaline and Motorists find themselves behaving in unbelievable ways (with a lethal weapon at their service).
Here is an axiom which has served me well on the not-so-mean streets of Salt Lake City: "Everyone on the street is in a terrible, terrible hurry ... all the time. Even people on the way to a triple root canal deeply resent any kind of delay".