Where I work, and in most US airports, no chairs are sitting around for you to use, and if you see one, you can't just grab it. When you make your reservation, you will be able to request wheelchair service. Upon arrival at the airport, you need to ask an agent to call for the wheelchair service; it won't be waiting for you because they have no idea when you are arriving.
I agree that this isn't complicated and there is no reason not to let the people who push the wheelchairs make a living.