There are blood pressure medications that have potentially fatal withdrawal syndromes - if you are physically dependent on them and you miss too many doses, it can kill you. That sounds like it should be the ultimate addiction. But people don't crave these drugs and if they don't know how dangerous the missed doses are, they fail urgently to seek them and even forget to take them. Also, because these hypertension medications improve health rather than do harm, it's difficult to see patients who rely on them as addicted.
Similarly, some antidepressants can produce a wicked withdrawal syndrome when stopped abruptly - but they, too, have no street value and no one has been known to rob pharmacies to get them. People can and often do forget to take their antidepressants - but no addict ever forgets to take their heroin. That's why even though some depressed patients are not able to function psychologically if denied medication, it makes little sense to label this situation as addiction, either.