Compensation based on outcome is one thing, but we're also talking about punitive damages here, not only compensation, and in the case of drunk-driving, it's 100% a matter of punishment and not compensation.
We can be a bit inconsistent on that, and I'm not yet convinced that punishment based on outcome works -- if a particular form of negligence is something you learn you can get away with, the maximum penalty in the event of the worst possible outcome is not really going to constitute much of a disincentive...