The point is we don't really know who is innocent or not, because the incentives are so fucked. If you're poor and need to get on with your life, you take the guilty plee almost every time. Trial takes fucking forever, and it's very expensive.

What this means is the you can be charged with almost anything, and the odds are very high you will plea guilty, regardless of your innocence. There's basically no incentive for the police or prosecutors to show any restraint, they have a "get out of jail free" card in the form of plea bargains.