I'm sure you remember the failed policy that New York Mayor Bloomberg attempted to pass earlier this year, the ban on sodas 16 oz. or larger. It's not surprising that such a policy didn't work out as people need to make better choices on their own. However, I do agree that something needs to be done about the sugary drinks as so many people are obese.
One solution might be to stop offering self service for sodas at fast food restaurants. I don't know how many times I've witnessed people refilling their large sodas at McDonald's. Not only have these people ingested what was probably a huge meal full of calories, they went and piled more sugar and calories on by having 2 or 3 servings of soda. I think the only self service machine should be for water, coffee or unsweetened iced tea.