Opium production, more than 90% of it anyway, takes place in the occupied territory mostly because it's geographically suitable for the opium poppies. The crop producers have protection in the form of the occupation forces.
Unlike marijuana, opium poppies cannot be grown in attics in Liverpool, Newcastle or Glasgow.
That American restaurateur, who is actually little more than a puppet mayor of Kabul but was made "president" by his puppetmasters early in the occupation, has been a godsend for the opium trade in Afghanistan. That's why heroin is more available on the streets of Europe and elesewhere than it has ever been.