Which I see as a total imbalance of justice. The same often occurs even if cyclists aren't involved. Incompetent driving leading to death BAC<0.05 equals life continues as normal. Incompetent driving leading to death BAC>0.05 equals ten year prison sentence.
Personally I don't see it quite so black and white.
It's more about what can be proven in court. There is no law mandating a minimum level of driver ability (beyond a test to get your license once) and no simple way to test and quantify driving ability after an accident. There is however a law mandating the maximum amount of alcohol in your blood while driving and it is easy to test for and prove. It's not that one is more important than the other, just that one is easy to prove and the law is a lazy thing.