Some people truly are unaware and/or so self-absorbed they have no empathy for their rudeness.
On the road, all that is left to us is to use the horn (or Road Warrior front bumper) to alert someone of their hazardous or bonehead move. Stationary, as in a public lot, unless they're aware of their boorishness, some might only be aware by 1) leaving a note and/or 2) leaving evidence of someone's anger. Fake fecal matter on the windshield might be over the top, but a well-place 16p nail is pretty effective if not subversive.
I understand how some might want to vent their anger on the perp's vehicle, but a "Dear A** H***" note (downloadable from page X in this thread) might provide some temporary relief, and is suggested if only for one's karma.
Bill's face-to-face scenario is noteworthy if true
. It can make people more aware and even mimic responsibility (nice concept). At worse, the interaction can also remind us there's a small minority of unrepentent zombies in our communities.
Sherwood