Inmates deserve every bit of harsh treatment they receive in my opinion. They obviously did something harmful and negative to put them in jail so if they want to commit crimes and harm other people then they deserve to be overworked and receive bad treatment while they are in jail.
Inmates in most prisons have access to not only three full meals a day but also doctor's care, prescriptions, and education all for free. If a prison or jail requires inmates to hold jobs or complete tasks while serving their time then there is nothing wrong with that. Why should more money be spent to pay someone to do these jobs when there are perfectly able bodied people in prisons, riding on the tax dollar? It's not hurting them to put in a few hours of work every day, they could probably handle a little more work to be honest.