Reward behaviour you'd like to see more of.

If someone provides efficient accurate polite cheerful service at your table, and you'd like to see more of that, leave a bigger tip. Same principle applies to anything else you want to encourage. It's called "vote with your dollars" or "put your money where your mouth is" and we have just as much right to do it as anyone else. It's why I bought Coppertone instead of other brands of sunscreen lotion, until they changed their design on most items.