TFA claims that prisons have failed. I don't entirely agree. The way I see it, prisons have three roles: one is reeducation, when we release someone from prison, they should come out as better citizens, not better criminals. In that respect, you could say that prisons have failed.
The second role of prisons however is punishment: prison SHOULD be an unpleasant experience for someone who has committed a crime. It should be a deterrent, something they will never want to experience again. Also, if you're a victim of a crime, you want to know that the criminal actually gets punished and doesn't get off with just a slap on the wrist.
Finally, the third role of prisons is protecting society, taking dangerous individuals out of the loop for a considerable amount of time so that they can't do any harm.
It seems to me that while GPS tracking devices may help somewhat with role 1, they don't do anything for role 2 and 3. So in my opinion, they shouldn't be a replacement for a prison system, but an addition to it, for instance in combination with the parole system.
I've noticed several design suggestions in your code.