Yes, it is. And contrary to the assertion of the article, this sort of thing happens pretty much in every town in the US.
If you owe the court money and you don't pay ... you'll be thrown in jail. Can't pay the fine? Jail. Behind on your alimony payments? Jail. The government always gets paid.
The worst part is that the people who get caught up in this are not exactly model citizens. Not exactly a clear case for sympathy.
Regardless, debtor prisons are barbaric, period.