You can see the prisoners toiling in the fields along every road a prison is located at, and there were several along the routes I drove weekly.
The US-Korean SOFA (status of forces agreement) was amended in the mid-2000s to segregate US military personnel in Korean prisons from the general population and:
1. Allow them to bathe at least once every five days
2. Prevent forced labor requirements from exceeding 12 hours per day
3. Provide food prepared to the standard of the US military in lieu of Korean food
4. Provide undergarments like underwear and socks to supplement their prison-issued smocks
https://www.usfk.mil/Portals/105/Documents/Publications/Regu...
Prior to this change labor often exceeded 12 hours per day, the physically larger US personnel were collapsing due to malnutrition, bathing was not permitted, nor were socks and underwear.
When I was there, pre-SOFA amendment the briefings were very detailed about the conditions under which prisoners lived as part of a "scared straight" initiative-- "Don't fuck up or you'll wish you were in Leavenworth, here is the shit, with photos, of what South Korean prisoners go through."
A British consulate guide notes the meagre diet and harsh conditions prisoners operate under.
>Meals are adequate, but very Spartan. British Nationals sometimes cannot fully adjust to the Korean diet. Funds from the prison work programme can be used to buy a small quantity of supplemental foods.
>The Korean authorities do not tolerate dissent from prisoners (e.g. assaulting or talking back to guards, or for refusing to co-operate or follow instructions). Their methods for handling dissent can be harsh, and on occasion has resulted in physical abuse. Such abuse is unacceptable, and we will take it up with the Korean authorities on your behalf if you so wish. You may also raise it with the National Human Rights Commission (NHRC).
https://assets.publishing.service.gov.uk/government/uploads/...