Frankly, most of the people I see in prison have a range of mental health issues; it's a spectrum. We all have that in the sense of how well we're coping with life. We all have mental issues at one point in our lives. The majority of people I see in the provincial system are not psychiatrically ill patients who require transferring to a hospital, but they do have difficulties with their mental health.
For example, we all use the example of Ashley Smith, because that's probably why you're studying this issue. Ashley Smith started off as a troubled teenager. Was she psychiatrically ill? No, but she did have some difficulties, and obviously her difficulties worsened with time.
I think what you're saying is once you've sentenced them, you could then suggest that they all need a therapeutic environment, yes, and they all need assistance. Can prisons provide that? With the correct warden and the correct atmosphere and with community partnerships it could be done. It means you would look at changing your ethos for correctional facilities.