Don't be an irritable inglubion! That may be the only interaction with a human that old person had all day long.
Be patient, you may be that old person, some day, and you'll appreciate the patience of the folks in the line behind you.
I already AM an old person and it would never enter my fading mind to make other people wait while I chat about trivia. My late parents, grandparents, and in-laws also had times of loneliness or isolation, but they were aware enough to know that other people behind them on the road or in the check-out lane were busy and didn't need to be inconvenienced. If I need someone to talk to, the check-out girl at the supermarket is not really the best choice because she's supposed to be working, focusing on her job. Distracting her beyond "Plastic, please," is not helpful. Posting HTML
When I was young there was a period of time that I worked odd shifts and shopped in the stores during what must haave been senior shopping days. I would be in the produce department and older people would hold up a vegtable and ask me if I could tell them how to cook it. Same thing in the meat department. Took a couple of times before I caught on, well-dressed lonely people looking for conversation. I would chat for a bit and smile. Grace is a gift we all need.