Is cannabis not physically addicive?

It is. It is absolutely, positively physically addictive even if the intensity of the withdrawal is less than other substances.
No. It is not physically addicting, and it is common for heavy users to suddenly stop and to have no withdrawal symptoms; even with high doses of hashish. Of course the symptoms for which they use cannabis recurr. Some infrequent person develops a psychological "dependency", but so do many people develop a psychological dependency to food.