It doesn't. But I used to go to a coffee shop and the lady knew my order. She had my coffee ready just how I liked it as I walked up to the counter.
She earned her tips from me.
When I was a waiter, I had some "regulars" who always asked for me. We'd chat, and they were really friendly. When they'd come in, I'd immediately bring them their preferred drinks. And every now and then, I'd buy them a round. In fact, on their Anniversary, I took care of their bill altogether.
After we became friendly, I don't think that they ever left me a tip smaller than 25%. And on their Anniversary, their bill was in the neighborhood of $75.00, and I was left a $60 tip! The nicest thing that they ever did though, was when they came in with their (adult) kids, who bought them dinner. Their kids left me a 15% tip, and after they had left, came back later than evening and gave me an additional $10.
To put it bluntly, if you're working for tips, and you really bust your butt, giving the best service you can, you'll do well in most cases.
Mark