Why is price gouging legal for jails and prisons (Texas???)?

A Top Ramen noodle soup at the grocery store costs on average 16 cents, why does it cost .75 cents to jailed folks here in Harris County Texas? A local call from a payphone costs on average $1.25 but jailed people who are LIMITED TO LOCAL CALLING ONLY have to pay $5 and $10 bucks a call! IMO this is hypocrisy at it's "FINEST".