When people are commuting, they are thinking of one thing mainly -- getting to work (or home) on time. Anything that impedes their progress ticks them off. I encounter the same attitude when driving to work. Some drivers weave in and out of lanes, ride other cars' bumpers, honk or flash their lights if they thing someone is driving too slow, blow their horns the second a traffic light turns green, yak or text on their cell phones. Fortunately, most drivers are not so nasty, and most of them treat cyclists with respect, but it's the small percentage of jerks that make life unpleasant for everyone else.