Addiction and dependence are two completely different things. Let me explain:
People on a steady dose are dependent on it to function. If the drug is withdrawn suddenly, they will feel ill. If the drug is tapered down slowly, they will be off it and need little further care. They don't crave the drug although they might wish there was something they could use to treat the pain they have.
Addicted people are different. The AA motto of "one is too many and a thousand isn't enough" applies to the addict, who craves more and more of the drug (including alcohol) even if he's flying high on it. You can taper them off the drug but if the craving is there, they'll go right back to it unless they get a great deal of follow up care, usually for life.
What we're seeing as "the opioid crisis" is a direct result of overadvertising and overprescribing long acting opiates, OxyContin chief among them, to both acute and chronic pain patients. They differ from most older drugs because they are timed release, long acting drugs, providing 24/7 pain relief. The problem with that is that tolerance starts to happen within a few days, meaning if the person is still in pain following surgery or with serious illness, the dosage will have to be increased. This is not good because eventually you're going to have a person whose pain might be gone but who is dependent on a high dose of opiate drugs. If they try to stop suddenly, they get sick and frightened.
Some of them have turned to street drugs and they're the ones who are dying since street dealers never know when the stuff they're selling (even the lookalike pills) are laced with fentanyl or other incredibly potent synthetic opiates. If more doctors realized the problem and tapered their patients who have taken the long acting drugs down, quite a bit of this "crisis" could be solved over time. That requires monitoring and more scrips for drugs, though and the DEA is hostile to that idea.
Oh, and opiates aren't the only drugs that produce dependence. SSRI antidepressants and glucocorticoids like Prednisone also do. Stop either of them suddenly, you'll get really sick.