Loyalty is another one. I'm very regular at the cheese counter at my local farmer's market, spending ~$20 most weeks— it's ended up where I'm on a first name basis with the guy who is usually there. He never weighs any of my stuff, just lops off big chunks and is like "sure that's about the right amount lol." Based on the grocery store prices for these cheeses, I'm pretty sure he's giving me a 30-50% discount.

But part of it is probably also that I'm very easy going; I'm happy to take whatever it is he's trying to move, and happy to grab chunky ends or other pieces that would be annoying to cut, etc.