Re: It's all about the presentation
Every study I know of has concluded that crime rate has almost no correllation to severity of sentencing. A person who commits a crime has either acted "on the spur of the moment" or has no intention of getting caught. In both cases they have absolutely no consideration for the sentence they might get if convicted.
Things that reduce crime are (1) increased probability of getting caught and (2) reduction of the factors that cause crime in the first place (e.g. inequality of weath, environmental factors such as street lighting, road and building layout as just two things.)