Costco allows members to fill their tires for free, they have self serve air stations near the tire center. No one checks for membership. Yes it has been getting harder to find free air for a while now and most of the times the pay stations are vandalized.
Once, I tried to do this on my own. I was looking at the machine, trying to figure it out. A man drove up and offered to help me. He put my money in, filled his tires, and drove away. I went home and told my husband to take care of it himself.