Because most of the criminals shouldn't be criminals. Most people in prison are there for pot possession, which should not be a crime. As for rapists and murderers, fine. But not that 15-year-old kid who smoked a joint while black.
We should gather up all the police departments that have taken military surplus equipment and send their asses to Iraq and Syria to battle with ISIS. As long as either side wipes out the other, we win. If they both kill each other, so much the better.