It is a somewhat incorrect assumption, since Russia has both words for Motherland (Rodina) and Fatherland (Otechestvo), both used quite extensively. Reasons for people thinking Russians only utilize the first one are usually of pop culture sort, and usage of Fatherland is also widespread. For example, The Great Patriotic Wars of both 1812 and 1941-1945 literally mean "The Great Fatherland Wars".