It’s because most people saying this shit live in America where all prisons are for pure cruelty and punishment, not rehabilitation.
You see, here in America prisons are an industry that generates profits for stakeholders. True rehabilitation would cut into their profits, therefore they do everything in their power to ensure you never leave, and if you do they will leave you with enough mental trauma and behavioral issues that you will return.
Corporate media propaganda ensures americans continue to support this shit just like all the rest of the fucked up shit around here. Thanks corporate America!