Earlier quoted context omitted.
A fall is an accidental death. When someone chooses to get behind the wheel of a car after drinking, they are intentionally making a bad choice. Getting to near zero drunk driver deaths is attainable once we change behavior. That's the acceptable number.
Would you include getting behind the wheel if you are tired, sick, stressed, taking antihistamines, or impaired in any other non-illegal-drug related way as well? Because I'm pretty sure those can impair drivers to the same degree. It's just that driving while impaired due to drugs is seen as being a moral failure, while it's perfectly socially acceptable to drive in other circumstances.
We can measure blood alcohol so we can estimate the degree of impairedness. Furthermore, it is already illegal.