Earlier quoted context omitted.
As far as I can tell, JPay is picked because it's the biggest. Any evidence the competitors wouldn't do the same once they got the contracts?
Write it into the contracts that they cant? The government is the entity with power here. The government regularly dictates all kinds of terms for their contracts. All the time.
JPay’s rapid rise stems in part from the generous deal it offers many prison systems. They pay nothing to have JPay take over handling financial transfers. And for every payment it accepts in these states — prisoners typically receive about one per month — the company sends between 50 cents and $2.50 back to the prison operator.
The government does have the power, and they most likely are outsourcing this part of their non core infrastructure like most other companies do, to save money.