It's punishment, which leads to the average american cheering and saying "yes, more!", meaning more support to the system.

If they turn off or down the light and someone injures another or gets seriously sick then there is a lawsuit.

Layers claim the guards didn't notice because the low light.

Jury finds that is a factor and awards.

Now it is policy in all detention centers to keep light on.

Lowers guard costs. If you turn down the lights, you need more guards and they are more at risk. Lights on, they can easily see and react so you need fewer.

More detuctable costs

Weakened inmates hopefully will not start a riot.