One of the goals of anti-distribution laws is to quell e.g. a local market for foreign exploitation. It's similar to banning the trade of ivory - sure, it's illegal to hunt elephants in most jurisdictions, but it's sadly hard to enforce in some parts of the world. It's even harder to enforce when the promise of wealth inspires the desperate to violence - hence the goal of e.g. "conflict free diamonds" as well. It's taking the laws of supply and demand, and using them to apply an economic answer - reducing demand - to reduce supply.