There are two different axes: the severity of the punishment, and the predictability of receiving that punishment. Severity, applied spuriously, doesn't really

There are two different axes: the severity of the punishment, and the predictability of receiving that punishment. Severity, applied spuriously, doesn't really provide a meaningful deterrent. A less severe sanction, applied predictably and reliably, does. If the way you operate a motor vehicle causes a death, you should be charged. If there were a meaningful risk of jail time for bad driving (including driving tired, speeding, driving recklessly, etc), people would either drive less, or would drive more carefully.