This is just stupid. Unrealistic. I am not talking about inhumane - it's expected, and humans can be quite inhumane in general (take a look at all those putinists and the like). The concept itself simply does not make sense. Prisoners are a valuable resource. You are expected to use them in some way. It is also part of rehabilitation process, since work can help with various stuff. They also waste resources, often quite a lot, especially if the rehabilitation fails, but still. They are kind of investment, at least: you invest into rehabilitation, in hope, that after some time the person "normalizes" and becomes even more valuable after reintegrating with society.
I know this is a bit idealistic, and reality is a bit more complex, as well, and you do need to punish some as well. My point is, that you either use a person as a resource or you discard of that person right away, so that you do not waste your own resources. What we have here, though? Not just isolation for extremely prolonged time (7 years for the main character), with no real hope for water or real food, but also... Box is powered by electricity, and clearly needs some regular maintenance because of the moving parts.
So, on one hand, you are not willing to use the resource (since isolation, no work, no water/food), but on the other, you are, since you wasting electricity and possibly humand-hours to maintain the boxes. Why? Just for cruelty? But this is supposed to be justice in this world, especially with the idea that some random citizens are expected to give you water/food at their discretion. Which, obviously, would not happen (unless it's required to move the plot), because why would people go to some stony beach to look at a box?
Otherwise, I guess it's fine from perspective of cinematography, but I was not able to watch this, when I cannot believe the premise.
