It is the same old story.
Kill 3 people with a knife or a gun, get life.
Kill 3 people with a car, 13 years is actually a very long sentence for this. Sometimes it is much, much less.
There is another thread on here linking to a petition for longer sentences for causing death by dangerous/drunk driving.
It is moving very, very slowly. No idea why. I think many people don't care until it happens to them.