I guess it’s a survival technique. Back in the days when chances were pretty good that a wild animal could leap from the underbrush and eat you, it was helpful for humans to observe patterns. Being able to notice a certain kind of twig snap before the mountain lion attacked went a long way toward ensuring a future generation. These days, distracted drivers yammering on their cell phones may be the new mountain lions, but our behavior is the same: we are hard coded to look for patterns.
I think that’s where this “sides” business comes from. Based on the slimmest of information, we immediately want to put people into a certain category. Somebody who attends church is lumped in with all religious zealots. A person who encourages recycling becomes just the same as all those environmentalist nutjobs. Of course I do this kind of thing all the time. (And I hate it when people do it to me.)
So the idea for this cartoon came (as they often do) not so much from observing other people’s behavior as from reflecting on my own. Which is to say, from the stark realization that I can be just as annoying as the people I find annoying.