Your argument comes from the idea that these criminals are logical and have good reasoning skills. On the contrary, most believe they will not be caught and take advantage of weakness when it is shown (like one person walking alone when there are ten of them.) As it stands, would it be better to execute them now or release them in 20 years where they could become a repeat offender at another woman’s or women’s expense?
It appears that Sweden is very bad about catching rapists. They also have super lax laws on murder, with 10 to 18 years or possibly life in prison for murder. While -18yo get a max of 14 years. They do brag about their low prison numbers and their re-offender rate being around 40% (Sooo, nearly half are repeat offenders? That is too high for my liking)
Better to have a living victim and a living criminal in prison than a dead victim and a criminal that may remain on the loose and not ever get caught at all.