It's unclear if the decline in prisoners stems from a decline in crime. While I generally believe the statistics that violent crime has decreased, it may be the case that the judicial system and even the government in general just have no enthusiasm for prosecuting or punishing it.
In short, no, they won't stop locking it up. They wouldn't even if there was a decline in petty crime... those locks are so that they can staff the store with 2 people instead of 5.
In short, no, they won't stop locking it up. They wouldn't even if there was a decline in petty crime... those locks are so that they can staff the store with 2 people instead of 5.