Appreciative, considerate people usually tip and also give seasonal gifts. Service techs, mail carriers, mechanics, are accustomed to receiving gifts during the holiday season, and they are very appreciative.
Those who tip, usually "get taken care of", you might even say they're VIP's. Mechanics just have a better attitude when dealing with a smiling, appreciative person...and that person will always be looked after. In home service techs will render superior service to those who are considerate.
Ever send a thank you card to a customer? Same thing. WE appreciate your business.

It's just a personal, "Thank You".
I enjoy tipping and showing my graditude.
Buddy