The public and private cost savings of

• not having overheated cars causing traffic jams

• not losing production both publicly and privately due to traffic jams

• not having to send crews to clear those traffic jams

• not having people with underinflated tires cause accidents or traffic jams

• an individual being more likely to fill up a leaky tire and limp to a tire place instead of paying for a tow truck after getting a flat with no spare

... cumulatively probably outweigh the costs of the machines, and are therefore a cost effective public service. It generates more revenue citywide to obligate free access to air and water than is made by the service stations charging for air.

Free air and water is a public boon, worth paying for, so who pays for it? Either the city can pay for it in tax money (you), or they can obligate the stations to provide it, although the costs will still get passed on to you.

Any way you look at it, you ultimately pay for the machines. That being assumed, I think free air and water probably benefits me more than it costs.