But that is because they have a population 10 times smaller than ours, in Singapore 1 in 10 people are below the poverty line, in the UK it's 1 in 5, law enforcement is efficient - if only the same could be said here! and there is a strong sense of community and social responsibility - here it's everyone for themselves.
If there was no death penalty in Singapore I would still expect their murder rate to be very low compared to ours.
I think it makes absolute sense to encourage good behaviour in prison with perks. It's a form of control really, like treating them like kids. Be good and get rewards, be naughty and we take them away. The punishment for the crime aspect of prison is a loss of liberty and that's enough. It's safer for everyone this way.