Random thought on the economics of coffee shops:
When I am doing work in a shop, I typically won’t be buying food, but am aware that I am not the most lucrative customer they will get, so I try to tip well. This leads to an odd situation at my most-frequented place: I can get a pot of tea for under $4 with a cash discount, and so will typically get a pot of tea with a $5 bill, and leave the change as tip.
However, sometimes the barista will forget the discount, and here’s the problem: do I point out this mistake? I’ll still be leaving a (noticeably smaller) tip, and so no matter what, I am spending $5. In some sense, I am helping out the barista by pointing out the mistake, but then: is it really worth it to either of us to have this conversation over $0.50? The conversation has been surprisingly confusing in the past, especially when I take the extra money I just made a point of getting back and leave it in the jar anyways.
Also, I would assume that most shops price their coffee based on what (they expect) will maximize profits. I imagine the pricing would be different if the goal would be to maximize tips (I’ll leave $1.50 on a $2.50 coffee, but $0.60 on a $2.40 coffee). Likely the answer would be different again if the goal was to maximize profit+tips, but the tea is cool enough to drink now.