Many addicts stop after several years of sobriety, accounting for fewer smokers at AA meetings. In countries where a far greater percentage of the population smokes, this is not as useful a clue to addiction. Because there are no accurate self-administered tests for addiction, these assertions can't be proven.
Accurate statistics require accurate reporting, a contradiction in terms in the field of addiction.
I suggest the odds are also substantially greater in a smoker similarly inflating his ego by yelling, or otherwise becoming visibly agitated in non-driving situations. The idea in identifying addicts is to look for destructive and other ego-inflating behaviors. This is applicable to the celebrity or politician you don't personally know, as well as to the anonymous smoker who carelessly tosses his cigarette butt out a car window. Addiction in those you don't know may affect you only temporarily although, when unlucky, a fleeting connection may seriously affect your whole life. The impact, however, by those you know is usually far greater.