What I understand of your post is that by lowering the threshold, drinkers are incentivized to keep drinking because they are going to get busted anyway. The result is drunker drivers on the road.
That makes sense. Unfortunately, when did government bureaucrats ever demonstrate an elementary ability to discern common sense?
What really bothers me is that our leadership is continuously getting more stupid. There was I time when I thought they couldn't get any more stupid. They surely showed me a thing or two!