The world is full of perverse unintended consequences in response to government attempts to eradicate markets, even when there is a well-intended reason for attempting to do so (usually to "save the children"). Fewer children drinking, using, driving under the influence or being sexually promiscuous is clearly a good thing. Does that mean that we should advocate for a monolithic policy of prohibition or should we take a more nuanced approach?
We certainly learned this lesson the hard way during prohibition. The prohibition of alcohol led to more crime, and while some individuals may have done without, significantly more folks simply used and produced alcohol more recklessly than they ever would have before prohibition.
There is also considerable dissent against the stupid war we are waging against drugs. This policy has driven the price of narcotics through the roof, created a monopolistic cartel market structure that has introduced an incentive to engage in violence to capture profits and other rents, and created entrenched bureaucracies in government that distort information and lobby for higher budgetary allocations and/or rights to retain money and property seized in raids. (A nice paper on this is Benson, Ramussen, and Sollars, “Police Bureaucrats, Their Incentives, and the War on Drugs,” Public Choice 83 n. 1, 21-45, 1995.)
Zero-Tolernce and lowering absolute thresholds in DUI laws also doesn't work. Under 0.10% BAC laws you've got a window of about 3 drinks before you're over. Basically, it has a divergent effect on use: a few more drinkers will abstain knowing that if they drive at about two drinks they're over the limit, but it raises the BAC levels of other social drinkers who drive after a party because being over the limit at 3 drinks is not much different from being over the limit t 5 drinks once you're caught. My friend Darren Grant has a neat forthcoming paper in Economic Inquiry on this.
If that weren't enough, check out this article from the Economist. Basically, Britain is trying to get kids to drink less by forbidding it, and forcing pubs to show more diligence in enforcing the 18 or older law on drinking. As a result, more teens are abstaining, but their volume of use is on the rise! As it turns out, for kids who were sidling up to the bar at 17, 16, 15 years of age, the old drunks and bartenders actually did a pretty good job of keeping an eye out and keeping them from obliterating themselves. Neat!