In the US, if you're in jail, you have to make phone calls through whatever provider the jail uses. These are private companies and charge a lot of money to the family just to talk to their loved one. A quid pro quo is a reward or advantage in return for something. In this case, the jails receive extra money for letting certain phone companies be the only ones prisoners can use. By preventing in person visits, they are lining their pockets with even more money. It's disgusting.
However, why would a prison allowed to profit on something like this? Where'd the money go to?
I mean, WHAT YEAR IS IT!?
Phone call is basically "ancient" technology by today standard.
Even better if they use VOIP or internet-based phone/video call. That would cost them very little to install and operate.