"O.K., that's an overstatement. But both concerns about the health effects of urban layouts and attempts to deter certain kinds of consumption are basically about the failings of rationality as a model of human behavior. People should get enough exercise - they will, in general, be happier if they do - but they tend not to get exercise if they live in an environment where it's easy to drive everywhere and not as easy to walk. People should also limit their caloric intake - again, they'll be happier if they do - but they have a hard time resisting those giant tubs of popcorn."