Maybe that’s because the change was so subtle at first. People stopped saying thank you and please. In the busyness of life, few noticed.
Then coarse words began to creep into everyday language. At first, they had the power to shock, but soon they became the new normal.
Voices grew louder, but people grew used to the din. Only action, outrageous action, designed to provoke, got attention, and getting attention was now the point.
Anyway, for anyone who might still care, at some point, almost imperceptibly, manners went out of fashion.