I have a hard and fast rule now:
If I have to drive to get the food (pizza takeout, etc.) or order standing up (coffee shop), I don't tip.
If I'm sitting down, you're bringing the food to me, keeping my glass full, I'll tip.
If I'm at a golf course and grab a beverage at the halfway house, sorry, you're not getting a tip for turning around and getting a beverage out of a refrigerator.