This study says that the death penalty actually costs more on average than life imprisonment.
Also, by castrating rapists/child molestors/etc, you might discourage some potential offenders from doing anything, but if someone is sick enough in the head to plan out how to Snuggle kittens with someone/molest a kid, then, under the whole "castration as punishment" thing, then they'll just decide "Well I'll have to be really careful and not leave any witnesses," which would probably lead to the deaths of the children they molest.
Or, what's also likely is that since sex crimes tend to be committed by people the victim knows (Family, close family friends,) and if you were close to Uncle Diddle, then if you learned that he molested another family member, then no matter how angry you got at him, chances are you still wouldn't want to necessarily send him to his death/castration.
Also, by castrating rapists/child molestors/etc, you might discourage some potential offenders from doing anything, but if someone is sick enough in the head to plan out how to Snuggle kittens with someone/molest a kid, then, under the whole "castration as punishment" thing, then they'll just decide "Well I'll have to be really careful and not leave any witnesses," which would probably lead to the deaths of the children they molest.
Or, what's also likely is that since sex crimes tend to be committed by people the victim knows (Family, close family friends,) and if you were close to Uncle Diddle, then if you learned that he molested another family member, then no matter how angry you got at him, chances are you still wouldn't want to necessarily send him to his death/castration.