In our society, we have institutionalized the practice of gratitude. People say "thank you" without thinking, and without any genuine sense of thanks. It's become a meaningless courtesy, like "Goodbye," which originally meant "God Be with Ye."
“Thank you for being here today,” my mom would say to every cashier, bagger, customer service worker, etc. for as many years as I can remember. She would often get varying responses. Every now and then there would be a smile, or the person would strike up a conversation. There were even times that my mom would get a dirty look! When I was younger, I never really understood why my mom did it. Was she really thankful that particular person was bagging her groceries? Mostly I thought this couldn’t really be the case. She would even say it to the people who were rude. I didn’t get it.