As the number of criminals in prison increased, the crime rate dropped.
When criminals are in prison, they are not committing crimes (at least against people outside of the prison).
Hard to believe that the author disputes this. The numbers are clear.
You are exactly right.
It always amused me to hear people moaning about how much it costs to keep an offender in prison.
First, no one is in prison for a first time non-violent offense. It usually is the last resort for criminals who cannot conform their conduct to society.
Second, prison, and to a certain extent the Death Penalty, is to discourage private revenge. If the victim or their family does not see justice being done, they may be more likely to impose their own version.
Lastly, the cost of prison is much less than the cost of leaving non repentant criminals out on the street...think of insurance, lost wages, continued welfare, and the incalculable costs of what crime does to a victim.