America hates poor people. To put an even finer point on it, America's poor people hate poor people - and the rich do whatever they can to facilitate that.
There's a long standing tradition in the world that predates America (even though we're the best example of it currently) of conflating wealth with morality. The entire eugenics movement was based in this tradition, I think. This might be a political stunt by the public defender's office, but it sure as hell is a good one. I completely reject any arguments that the judicial system should be any part self-financing. If there's one thing that we should agree as a society that's a shared cost, it's public safety. That's the most basic function of government. Government isn't a business, and it shouldn't turn a profit. If we're going to arrest and prosecute people, we need to pay for it. Lots of people need to be arrested and prosecuted, unfortunately, but suffering the cost makes us not interested in distinguishing between much needed arrested and unimportant ones.