18,000 people died in 2006 from DUI crashes.
That's 4,000 more than homicides. So yes, it's pretty "heinous" and should get "insane" punishment. The problem is the punishments aren't insane enough; they sound "insane", but the criminals just get right back in their cars and kill/main more people.
Every time you get behind the wheel and you're drunk/high, you're loading a handgun with a bullet, spinning the chamber, and pointing it at innocent people on the road, and pulling the trigger.
The difference is that you're very often driving to a store where they happily sell you that gun and bullet knowing full well you're going to get into your car and play roulette with it.
No gun store in the country would sell you a gun knowing you'd do that, yet millions of bars serve patrons who drove to their establishments, knowing full well they're going to get back into their cars, drunk.