Seems pretty cynical to me too, but I've lived in either North Dakota or Minnesota for a couple of decades. It takes so little effort to be nice and have a conversation with people. Who knows, you might make the teller laugh and get through their day easier.

[from the article] Does anyone who has ever said “have a good one” actually mean it?

Yep, I do mean it. I'm that sap. I wish you well and still sign all my e-mail "keep safe". I mean that too. The world can be an unforgiving place, no need for me to not help you along.