I remember a recent thread about people who were either offended or refused to use the words Ma'am or Sir, in addressing people, for whatever reason.
Well, refusing to say please and thank you is just the next step in the destruction of a polite society.
Much of today's society walks around with a set of blinders on. They never see anything except what's in front of them, and then, only if it's going to get in their way.
Acts of kindness may only take a couple of seconds, and can lighten another person's load, for the day....Letting someone into traffic, at rush hour, off of a side road or a parking lot, instead of closing the gap, so that they can't get in.
Of course, if your head isn't on a swivel, you'll never even see that opportunity.