Privatization is an issue, but also cities or police departments that rely on such revenue will also push for systems that drive revenue since it is a significant portion of their budget. Here’s another piece that explains it: npr.org/…/paved-paradise-examines-how-parking-has…
It’s a pretty long piece which covers other aspects of parking, but if you start reading from this excerpt: “GRABAR: I think so. Essentially, parking enforcement serves as a subset of what is now known as revenue-driven policing. And the idea here is that cities take advantage of these parking laws to try and get as much money out of people as possible, but not in the way that you would think, right?” and onward, it covers how underlying problems aren’t solved because the revenue derived from the existing situation is too convenient for the city. They even build around that by giving certain companies discounts on parking tickets because of how often they get them from just trying to do their job.