About 1/5 of the inmates in Canada are there for violent convictions according the government of Canada website.
Most people would agree that, for a relatively small number of depraved violent offenders, kennels are probably more than they deserve.  

However, a significant portion of the prison population is there for drug related offences and property crime.  Many have addiction issues and/ or untreated mental health issues.  Many are functionally illiterate. 

Why are prisoners even given the opportunity to be in solitary confinement at all, for anything more than 24 hours?  There should be no idle time in prison. The majority of their time should be spent in behaviour modification courses and health courses on how to care for their mental illness. Drug rehabiliation courses should be mandatory for any inmate convicted of drug crimes.  Literacy courses should be taken by all prisoners and the better readers should be assisting others.  And work like laundry, kitchen, landscaping..