Centuries ago, Charles Dickens wrote about the problem of debtors prisons in England. Debtors prisons were also common in colonial America. We thought we phased out debtors prisons along with slavery in the mid-19th century. Well, we got rid of slavery, but debtors prisons are still with us. Nobody knows how many husbands and fathers are in jail for the problem of not paying, or not being able to pay, a small amount of money to an ex-wife which had been ordered by the court. Then there is the problem of older inmates who are particularly expensive because some require wheelchairs, special protection against younger prisoners, costly health care, and many suffer from dementia.
Of course, criminals who commit violent crimes should be locked up for the protection of the rest of us. But we need to have a real investigation to find out if our prisons contain a lot of people who don't need to be there because they are not a threat to society.