If you really want to control drug abuse, forget opinions and theories. Learn from others who have either succeeded or failed. There is ZERO drug zombies in Singapore. If you want the same result, learn why Singapore has succeeded. And they do NOT spend a fortune addressing incarceration or reforming drug addicts.
Learn from others and avoid mistakes, because there is not enough time make makes and recover.
But they do have them in other tough-on-drugs regimes like China and Iran - so contrary to what some have suggested on this thread, adopting Singapore's drug policies is far from a guarantee of getting Singapore's results.