Most parking spots might cost you nothing, but parking is never really free. We just pay for it in ways that are completely divorced from our actual consumption of parking.
Instead of paying directly for parking, the costs are almost always bundled into the price of other things we consume. These costs are very real — it takes a lot of land, material, and labor to build and maintain parking spaces — but in the name of cheap driving, we’ve made them invisible. Everything else costs more so that driving can cost less.
Pricing a good this way produces what economists call a market distortion. Because the price of parking is hidden, Americans purchase more parking than we would if we paid for it directly.