Interestingly, this sometimes works the other way around too. I frequented a coffee shop in my town for a few months (I later moved house). The baristas came to recognize my face, even though I didn't make smalltalk or introduce myself. I would come in, order a coffee, and work on their wifi for a few hours before leaving, more or less every other day.

One day the barista recognized me and said, "this coffee's on the house." I was stunned--stuff like that usually doesn't happen to me because I'm usually fairly quiet when it comes to interacting with service people. Grateful, I put the money I would have spent on the coffee into the tip jar instead.

Over the course of the next month the barista would occasionally offer free coffee again. The cup of coffee costs them cents, but it brightened my day so much that I actually started tipping (for the first time at a coffee shop, ever) regularly.

So in effect, for the cost of a "bribe" (a few cups of coffee to me), the barista had established a relationship that made me feel like reciprocating with cash.