Let me start off by saying that I don't approve of drunk driving. That said, the laws and how law enforcement treats drunk driving and how alcohol related accidents are reported tell a very distorted picture. After the MADD campaigns picked up sufficient steam and states began taking drunk driving more seriously, numbers dropped. But then they quit dropping. So many states lowered BAC limits from .10 to .08 in order to include more drivers in the impaired category even though there was no evidence to support it. With numbers stagnating again, you see another push for states to lower BAC levels to .05 even though there is zero evidence that this will lead to fewer accidents. All it does is create more criminals on the road which the police can then catch, fine, and profit from.
In the US, more people are arrested for drunk driving than for any other crime. Nearly 1% of all licensed drivers has received a DUI in the last 3 years.
As all of this was happening, the definition of what was alcohol related began to expand. Currently if any party in an accident is under the influence, even if they were not operating a vehicle, it's alcohol related. These inflated statistics then fuel calls for more oppressive crackdowns on drunk driving.
Again, I'm not advocating drunk driving but we have to focus on the right problems. Like, how do you keep the people who are the most dangerous off the road? While the police are out spending resources racking up arrests for people who had a couple of glasses of wine with their meal, a large percentage of accidents are caused by repeat offenders. Nationally, over 33% of people arrested for DUI get another DUI. And people with multiple DUIs are overrepresented in fatal car accidents (4.1x more likely).
Considering the fact that the most common BAC of someone who has been pulled over for suspicion of DUI is .16, continuously lowering the BAC threshold in order to snare more people in DUI convictions is not the answer. They're not the ones getting into accidents.
Believe me, if they changed the laws and made it a crime to serve more than two drinks to someone unless they could prove they had a ride home (other than them driving, of course), the alcohol companies would quickly come up with solutions.
Clearly the government's interests are not aligned with lowering drunk driving. Lowering drunk driving costs money (public transportation options, better city planning, etc). Arresting people for drunk driving generates revenue from fines. If they were successful in lowering drunk drivers on the road they would be decreasing their budgets.
Until you can align motives with profits, you'll never fix the problem. You'll just keep increasing the base of people who are considered criminals.