The heroin may come from Latin America, but the poppies could have been grown there, SE Asia or Afghanistan. S America is a transhippment point for a lot of dope produced elsewhere and destined for the US market, as well as a major producer all its own, particularly for crops like cocaine which are specific to that area.

Dope is like oil, there is a world market and many suppliers. For example, most of the North Slope oil winds up in Japan, as would any oil new pumped from proposed new offshore sites developed in West Coast US waters. The market determines where a product is sold, and many other cost factors besides shipping costs determine the market. Increased poppy production in Afghanistan may all go Europe, but that still means US sales opportunities for S American and S E Asian producers.

Isn't the market wonderful?