Many of the people who match the political community that I'm in are very fond of ad-hoc pricing tools such as mandates and subsidies. However, I believe that strict market controls have 3 main problems:
1) they are inefficient, because they remove the relationship between cost and demand.
2) they shift costs to disinterested parties, because any excess costs are borne by society rather than beneficiaries.
3) they are a burden, in that the effects of the policy must be codified and enforced, resulting in heavy administrative costs relative to the success of the policy.