I agree that stiffer penalties will not make everyone drive safely, but I bet if enough people start getting jail time for negligent homicide or vehiclular manslaughter instead of a failure to yeild ticket most people will take notice, which may save a life here and there. Not to mention the idiots that do this on a routine basis will get what they deserve, some private time with their cell mate!
I heard a story about someone's 88 year old grandma who killed three people in two separate accidents within 6 months of each other because she kept pulling out into traffic without looking. If she got jail time after the first offense, I highly doubt she would have killed the second victim. Her family would have stepped in and made her stop driving or something.
Oh well, who knows if the story was even true... I guess you are correct that all we can do is watch out for our own safety. I would still like to see the people responsible for fatal traffic accidents get jail time. Even if it does not make the streets safer, they deserve it.