by the mid-1800s, reformers became disillusioned with the since rehabilitation or deterrence was not being realized.

This could be a few things. Some became discouraged with jails. Some jails and hospitals had been created to rehabilitate the offenders, while some were, most became "repeat offenders."  Reformers also began to become disappointed with the political scene. They had voted for people whom had promised to change things and make things better. This didn't happen.