You prove my point with your post.
The law currently does not take into consideration human nature. By saying you can have X number of drinks , a good portion of people think they are in the category of X+1 or X+2 etc. If not we wouldn't have as many drunk drivers, and we certainly wouldn't have otherwise non alcoholic folks drunk driving.
The law is flawed, and we can see that by the evidence, how many otherwise good people have thought " I can handle my liquor, bring on a couple more beers before we go home." because of the fact that the law, as written, does not take into account the human tendency to think rules apply to everyone but them.
I mean hell, another great example, is the fact that places have to be very specific with any signage for any rule. How many times do you see "...and no exceptions." or something of that nature on parking signs, information posted when coming into buildings ( at my college, the biggest part of the "don't come to school with the flu." sign is the "With no exceptions." bit.) . Doing this, and even making it illegal to drive with any blood alcohol content, is the legal equivalent of saying " and no exceptions." because as we can see, people just don't get that part of it as it stands.