"People should be ashamed when they are passed on the right"
I'm not a bumper-sticker person. I really have never had one, and probably never will. I guess my soapbox-ish feelings have never overcome my greater aversion to more visual pollution. ...Except when it comes to driving considerately. If I saw one, I'm sure I would buy and apply a bumper sticker along these lines:
keep right (except to pass)
Driving considerately depends on awareness. If you're oblivious to what's going on around you, yes "mental auto-pilot" might keep you personally safe (somewhat), but it interferes with the effective flow of traffic.
This "driving oblivion" is essentially a form of laziness. People should be ashamed when they are passed on the right, and should feel the need to apologize somehow, perhaps by flashing their lights in acknowledgement of the inconvenience they may have just caused the passer. But of course they'd have to notice that too...
A similar symptom of driving oblivion is failure to indicate: just drift on over to wherever you feel like being, with no consideration for other drivers.
I guess flow and being considerate are big with me these days.
A not particularly-related frustration, but one which also breaks flow, is traffic waves. I think I mentioned once that I'd meant to write about it as a form of compression wave, but fortunately someone beat me to it. Traffic waves are actually not a symptom of laziness, but rather one of greediness -- never allowing enough space in front of you that someone else might be able to cut in line. In the process, your foot ends up back-and-forth between pedals, magnifying the compression waves and actually slowing the flow. (Imagine a sink drain that burps, back with the air, forth with the water).
(Normally I'd apologize for venting, soapboxing, etc. But lookee there at my name up top! Speaking freely is a blog's "why".)