> The goal of this idea is to encourage you to not attempt manslaughter with your vehicle, so if you were faced with life imprisonment perhaps you would think long and hard before you do it the third time.

This is the worst part of excessive penalties -- that people think they would actually be effective. Most defendants have absolutely no idea what the penalties are until after they've been charged with the crime, which makes any deterrent effect of increasing the penalties quite impossible.

Even if you ran some kind of expensive continuous education campaign (which naturally can't work for every category of crime because there are so many types with such complicated penalties that no one could keep track), you're assuming that people engage in planning. If people planned ahead then they would all have a ride home from the bar in the first place.