This is a discussion about personal morals. Some people think it’s OK to execute some criminals, others are completely opposed to that idea. There is no objective right or wrong here.

For you your arguments might be compelling, but they don’t convince me. I can have complete control over someone and still decide to kill them because I don’t want to bother with locking them up, for example. And who says a society should not kill? That’s not even an argument, just an opinion.