Now, how long do you think it would take for people to seriously re-consider driving themselves home from dinner that includes a drink or two?
Germany, as I understand, has (or had) a two strikes and your out rule with drunk driving. First time, you don't drive for a year, second time you never legally drive again. Result, very low rates of drunk driving.
I understand the line of thought you're on. I don't know how accurate or inaccurate be the conclusions you've theorized. The factor that plays heavily in my mind is that alcohol is a "mind altering substance;" it, among other things, allows one to perceive one is capable of doing things one truly cannot do or do well. Thus, I'm very hard pressed to conclude on whether the hypothesized impact would in fact materialize.
I'd be willing to try the model you've suggested and find out. After all, alcohol use is a nonessential activity and it's a behavior that requires one to exercise responsibility and good judgment before, during and after engaging in it. If a law will increase the frequency and quality of folks using good judgment re: alcohol use, great.
(I noticed you wrote that you haven't confirmed the causal correlation implied by the thinking you noted, so I won't hold you accountable for it being genuinely so, or for your being convinced it is so.)