I've been pondering this fentanyl situation for months.. as a tin foil hat wearing ex-junkie, I've come to the conclusion the reasons are much more malevolent than it simply being a cheaper product that's easier to ship..
The drug trade has already been controlled for quite some time by men in suits who (for the most part anyways) are too intelligent to touch drugs themselves.
Synthetic opiates ..oxycontin, fentanyl, methadone etc are much more addictive than heroin. Heroin withdrawal cold turkey is about a week. Synthetic opiates..a month at minimum, if you're lucky. I'm speaking from personal experience. Btw, opiate addiction is HELL.
A concept I think is genius but, at the same time, evil, is first begin lacing everything with fentanyl. Which makes every drug it's put into exponentially more addictive & mass overdoses begin.. So then money is pumped into distributing naloxone/narcan. Which, even though it does save lives, it has the effect of putting the recipient into withdrawal by knocking the opiates off the receptors. So, of course, they will just run back out and use MORE drugs.
Now here we are in 2017. All these drug users (the ones still alive at least) are hooked with addictions more powerful than humans have ever experienced. Power drunk men in suits say hmmm... now let's begin throwing even stronger drugs into the mix ie. carfentanil. Just to see how many we can kill off. Because that's just how the most powerful men in the world, the ones who actually have control over money and resources, roll.