re: opium crop
In the U.S., there are many other ways to make a reasonable living. It's not accidental that a lot of drugs are produced in the Third World. I assume if half our GDP came from opium, it might be a little harder for the government to crack down.
In the U.S., alcohol, the legal drug, does about $120 billion in business a year. When it was illegal, it also became closely associated with crime.
The problem is the customers, and the supply/demand balance, not the farmers. Kill every poppy in Afghanistan, and they'll just start growing them someplace else.