And this is taken from punishment 101 at your nearest liberal college or university? The only "careful" that needs to be watched for is making sure the switch is "on" and not "off".
No, it's from Criminal's Education 101. You can be sure criminals know exactly the punishment for their crime. Even petty theives know the line between misdemeanor and felony and avoid it carefully. Kidnappers know when it becomes capital, robbers know when it becomes capital - and all but the most inept do whatever they can to avoid capture and conviction.
If there is no penalty, only potential benefit, from killing the victim, criminals will very likely escalate the rape to murder.