Take your self-righteousness elsewhere.  I didn't say anything to "excuse" DUI offenders.  I made the observation (which I'm qualified by professional experience to make) that inexperienced drinkers often simply don't comprehend how insidious the effects of alcohol are--they think they're unimpaired when they're not.  

It's not illegal to drive after simply imbibing alcohol.  What's illegal is to drive "intoxicated."  The Alaska Supreme Court has held that "intoxicated" means "impaired"--which isn't very explanatory.  As a practical matter, it means above o.o8% BA.  Nobody alive can tell just by how much he's drunk or how he feels at the moment whether he's above or below that limit.  But more experienced drinkers can usually assess the risks--of both their driving ability and their blowing 0.08 or higher--better than 18-year-olds who've only just acquired the legal right to purchase and consume alcohol.