Policy makers and folks of their general ilk tend to assume that people will choose to do what's best for themselves if they have the opportunity and they have the information to ascertain what's best. Never mind that people smoking cigarettes (to say nothing of using illegal drugs) puts the lie to that assumption, it's still the general operating mentality. It's the same mentality that advocates for school choice, green vendor programs, and other social innovations designed to help people do what we assume they would want to do if they had the choice.
A study released yesterday from NYU and Yale puts the lie to assumption yet again. In July 2008, NYC restaurants had to start posting the calorie counts of their menu items right next to the item on the menu. The idea was that if I walked into a McDonald's I would know exactly how many calories were in a quarter pounder and, presumably, I'd then leave and go eat a salad somewhere. The only problem is that this study indicates that the program didn't work. In fact, it looks like people are ordering more calories in their meals after the counts went up, rather than less. Don't people just do the darndest things?
This is not, itself, an arguments against giving people more information and more choices. Neither of those are bad things. However, the idea that either or both is a panacea for whatever social problem we're trying to fix is simply false. Let's remember that before we put all our eggs in that basket.