I don't really think they do. In practice it's one of those things where you are mostly penalized bases on your wealth/resources- not that I'm sure that doesn't apply to anything. A judge/lawyer/connected/wealthy can drive drunk as much as he wants, but if you don't have resources you can do mandatory jail time for a false positive due to health conditions, at least in my state.
I would also add, I doubt Balko identifies as an an-cap, though I could be wrong.