That sounds uncomfortable. However, don't forget they are criminals those inmates. They are not in a hotel. So they shouldn't complain.
If you come to Thailand as a foreigner you are to accept the rules.
Also, about cruelty. Is it so? What about Guantanamo or Abu Ghraib prison?
We are here in Thailand, not in those areas where e.g. soldiers committing crimes continuously without any responsibility in court. Those soldiers are sacrosanct? But that is another chapter to discuss.