Policies that make pseudoephedrine harder to buy in order to deprive methamphetamine cooks of a key ingredient can indeed reduce small-scale domestic production, but the result is increased supply of a more expensive and more potent version of the same drug from Mexico. The environmental impact is less, but the social impact may well be greater.
It’s quite possible that timing made a big difference. If Sudafed supplies had been restricted before home-cooked meth had built a user base for the drug, the Mexican import trade might not have developed. And that may still be true in states where meth isn’t yet a big problem. But of course where meth isn’t yet a big problem, it’s hard to mobilize the political will to annoy the retail druggists.
If you think the moral of the story is that drug abuse control policy is always futile, I can’t agree. But if you think the moral of the story is that drug abuse control policy is hard, I’m with you.