Encyclopedia Britannica:

"Folk music: type of traditional and generally rural music that originally was passed down through families and other small social groups. Typically, folk music, like folk literature, lives in oral tradition; it is learned through hearing rather than reading. It is functional in the sense that it is associated with other activities, and it is primarily rural in origin. The usefulness of the concept varies from culture to culture, but it is most convenient as a designation of a type of music of Europe and the Americas.

"The term folk music and its equivalents in other languages denote many different kinds of music; the meaning of the term varies according to the part of the world, social class, and period of history. In determining whether a song or piece of music is folk music, most performers, participants, and enthusiasts would probably agree on certain criteria derived from patterns of transmission, social function, origins, and performance.

"The central traditions of folk music are transmitted orally or aurally, that is, they are learned through hearing rather than the reading of words or music, ordinarily in informal, small social networks of relatives or friends rather than in institutions such as school or church. In the 20th century, transmission through recordings and mass media began to replace much of the face-to-face learning. In comparison with art music, which brings aesthetic enjoyment, and popular music, which (often along with social dancing) functions as entertainment, folk music is more often associated with other activities, such as calendric or life-cycle rituals, work, games, enculturation, and folk religion; folk music is also more likely to be participatory than presentational."

There's a lot more, but there's nothing (as far as I can see) about deriving from or expressing a particular national, ethnic or regional culture. Who's deluded? Anyone who thinks they can rely on a one-volume paperback 'encyclopedia' published in 1997, I'd suggest.