Free parking is not free. There's a cost but it's spread out in multiple ways like taxes and the cost of products and services. On average the passenger car in the U.S. spends 95% of its time parked. While most everyone in America is focused on the 5%, UCLA economist Donald Shoup has researched and written a book on the cars 95% time parked.
One of his ideas is 'demand pricing' where the cost of parking changes throughout the day, for example, more expensive during the high demand part of the day in a city's downtown. Another of his critical points is setting the cost of parking so that each block will always have one or two vacant spaces. The video is 7:00 long: