the penalties for killing people with a car have always been less than for doing it with a gun or a knife. The sentiment behind this seems to be that everyone's a driver, therefore it could happen to any of us, and it would be most unfair to lock us up for ever just because some foolish pedestrian threw himself under our wheels. (I believe in olden days, when drivers were charged with manslaughter, juries would typically find them not guilty.)
Really, the whole country is geared to cars and drivers, so this is nothing new.