Deuterium wrote:
I've wondered the same thing sometimes, as in perhaps our society has developed so many underachieving individuals that we need to thank them when they do what they agreed to do in exchange for a paycheck? But without thinking into it too hard, I think they just enjoy the boost in confidence, with the added benefit that they would be less likely to be tamper with your food (in a restaurant scenario) if you were nice to them.
You say "thank you" because it shows that someone's noticed the worker is doing a decent job.
It's far easier for customers and managers to notice when someone does something wrong, than it is for them to notice when something is being done right. Saying "thank you" for even basic tasks is a small way of balancing things out.
A paycheck only covers the Safety and Physiological levels of the hierarchy of needs, a simple "thank you" goes beyond that.