Ever use an ATM with voice prompts? It's hard not to talk back to a machine that's talking to you.
It seems to me that the service-oriented "thank you" is more about expressing satisfaction than gratitude. It's a way of communicating that you have no complaints about the service without suggesting that there could have been anything to complain about. When a person doesn't say "thank you" it implies they were unhappy with the transaction and that they may be less likely to want to do business with you again.
Ever use an ATM with voice prompts? It's hard not to talk back to a machine that's talking to you.
It seems to me that the service-oriented "thank you" is more about expressing satisfaction than gratitude. It's a way of communicating that you have no complaints about the service without suggesting that there could have been anything to complain about. When a person doesn't say "thank you" it implies they were unhappy with the transaction and that they may be less likely to want to do business with you again.