Educating a person is materially different from getting them to act against their incentives. Doing so with a population is even more so.

The average American is overweight and doesn’t exercise. They are almost certainly aware they need to reduce their calorie intake and spend at least a couple of hours a week engaging in physical activity. Knowing you ought to change you behavior and actually doing it are completely different issues.

I actually happen to think that both are basically losing battles these days, but the underlying reasons aren’t the same.