Well where is all the funding going to magically come from? It would require massive budgetary and bureaucratic overhaul to improve the system. Sure, prohibiting private funding might be a small part of an overhaul, but it would be nowhere near enough on its own.

Why would it require any sort of overhaul? This stuff is already largely paid for by taxes. Fines and fees are only a supplementary source of income.

The article uses Benton County, WA as an example, and states:

"Benton County collects just a fraction of all the fines and fees it's owed. But the county still collected $13 million in 2012 — making it one of the state's top revenue producers."

The county's most recent budget is over $100 million. Law enforcement in its various forms is around half of that. $13 million isn't trivial, but neither is it huge in context.

If you cut the fines, you'd have to increase tax revenue by a bit more than 10%. Again, not trivial, but not huge.

Consider that the money is already there and already being collected, it's just that you're disproportionately collecting it from poor people. Surely moving to a system that collects the money more evenly would make it easier, not harder, to obtain that money.