If the market provides what consumer's want then, people should really spend money on changing what the consumer wants. For example, the environment loving liberals should work on educating people on their point of view, and win a large part of the population over. People will desire greener products, and the market will provide what they want. Just making laws on what people can and can't buy want change what they want, just what they can buy.
Also, with fighting the obesity epidemic, if you can change people to desire healthier products then the market will provide that need.
Of course in the end making laws is a lot easier than changing behaviors and educating, but it would be the ideal way to tackle some problems.