Recently, while taking the metro to work, I encountered something that shocked me. The train was pulling up, just as the man in front of me tapped to pay to go through the gate, and a woman pushed past me to cut me in line. I still made the train (after I briefly considered acting in a way that would have made us both late for work), but as I passed each stop I got angrier and angrier. Why did she think her commute was more important than someone else’s? We learn to wait our turn when we’re children — why was that lesson lost all these years later?  I’m not the only one irritated by...