Jam thanks for sharing
The point is
If you are buying gas at a station and need to use the gas hose you do not pay seperately for gas and the use of that hose. Also included with the gas purchase is air and water. If you need these things during your visit, paying for them would be double paying since you made the gas purchase and have a right to use the other (air and water) hoses. Before your post, I didn't know this was the case.
If you pull up to a station JUST for the air, and it is not a regular free service, then you have to and should pay.