Ok so that's where your wrong. We have a unique and very complex and balanced first world prison system.

You see in America we use public prisons in a unique way. They are a business model. In a public prison the Administration uses service providers to provide things like Telecom for friends and family, JMS(Jail Management System) for managing the facility and its inmates, Commissary for supplying inmates with products, and many other services. In addition as other people have stated several facilities charge rent this is almost universally a county correctional facilities thing where inmates tend to be people awaiting trial, awaiting sentencing, on temporary hold, or inmate serving less than a year. There are some county mega facilities though now that are longer term and also charge rent. Now lets explore how this ends up working. A telecom service such as GTL(Global Tel Link which is the largest provider in the US) will charge friends and family up to 30 dollars (highly dependent on the facility and the agreement with the administration and the state) to setup an account with all fees and make a 15 minute call. 90+% of that goes to whats called a commission. This commission is paid back to the facility for use of the service. If that sounds like a bribe to you YOUR WRONG you see this is perfectly legal in most states and not a bribe of a public official at all!(very recent legislation has change this in some states (3) but it is still very legal in most states). There are many many ways to bribe officials especially sheriffs but this is the most overt one. Remember its not the inmate who generally pays this as they have no real means of income though some opputunities (we will get to that) their friend and family deposit it into their account and generally that account is tied in with their commissary account and that's generally tied in to the JMS. The commissary business model works identically to the telecom model and these companies tend to offer a JMS essentially for free for obvious reasons. Many inmate especially in long term facilities just tell friends and family to not contact them in lieu of going broke. Thus disconnecting them from their friends and family completely which has a heavy impact on recidivism. Now the facility may have work opportunities as well and isn't it ever so convenient that the amount you can get paid from those work opportunities happens to be JUST about as much as the facilities housing fee. Funny thing to if you don't pay the housing fee while your in the facility the facility will take it out of you commissary account. So you either work as a slave or they take you ability to in the case of a female facility critically necessary health products(though most inmates resort to toilet paper). You see how wrong your were? This is a complex and very well thought out eldritch horror. The machinations of which truly boggle the mind. This isn't even the horrid private prison. This is a publicly funded facility. I could share the endless horrors of the American prison system but its a special hell of which I wish to open no ones eyes to fully.