While taking a rare trip one day on a suburban bus, I noticed a very small discreet sticker on the window next to my seat which read, “Do not enter bus through this window.” It was a source of great comfort to know that the authorities had given some thought to establishing which windows were preferable to use when entering the bus. There were no such signs on any other window. Of course, there was no explanation, perhaps it was obvious and I just couldn’t see it or maybe it was not my place to question such things. 

A strange kind of societal demarcation appears to...