Under capitalism all "law" enforcement measures are just class war in disguise. In a post revolutionary situation things are different.

I do think every person is capable of being rehabilitated but some people have caused so much harm that the value in their rehabilitation is greatly outweighed by the value in using their example as warning. Why try to fix a drug dealing and prostitution kingpin? What gain does it do to just warehouse them?

I really appreciate the Chinese model for corruption, "we caught you on this crime which gives us the right to kill you but if you tell us every other crime you can go to prison for the rest of your life. but if we find anything that you didn't tell us you are dead."

Corruption is a 2 person crime. So if you can catch one corrupt person and convince them to confess to all their other corruption they will lead you to their co-conspirators and each of their conspirators may have other corrupt contacts. By making them "an offer they can't refuse" they take down an entire system of corruption one individual at a time. Having the death penalty available is not just a good deterrence it is a powerful investigative tool.