Uum? You realize smoking is more addictive than heroin right?
If true, I guess that just means heroin is way less addictive than the PSAs would lead you to believe? I know plenty of people who have smoked a handful of times but never made it a regular thing.
I think the nicotine and opioid addictions are hard to compare.
Opioids (and heroin in particular since it's so refined and bioactive) are very intensely negative to come off of, but once you're clean (if you're a regular user, it's a few days of feeling more terrible than a really bad flu) you aren't addicted anymore. What's happening is the opioid receptors in the brain want to continue to be bound to the opioid chemicals, so you feel terrible while they are slowly detaching. And doing more heroin fills the receptors so you instantly feel great again--hence the addiction.
Nicotine changes your brain chemistry long term, and can take a very long time to go back to normal (if ever). It also has other habits involved (social events, drinking, sex, break times, etc) that are really hard to rewire. You're constantly being pinged by triggers to go smoke. And while you're using tobacco, your satisfying the nicotine addiction. When your nicotine source slows, you start feeling anxious, on edge, etc. The symptoms are less bad than heroin, but the effect lasts longer than just a few days.