Subsidy means govt spends more money on parking spaces than it takes out of parking spaces. In the city of Seattle rates for parking spaces are more than $3 / hour from 8:am until 8:pm, including Saturday (Sunday is still free). Most of the parking spaces are used at full capacity. This means that one parking space in Seattle would collect some fraction of $3 x 12 hr x 6 days / week x 52 week / year = $11,232 / year. Believe me - in Seattle these parking space have not been updated in decades. Govt spent no money and instead it got some fraction of $11,232 / year.

Parking spaces, in Seattle at least, are not subsidized. They are a massive source of revenue for the local govt.