Not going to get too involved here too much, in deference to Shirley Valentine, but Heylin's comments make perfect sense to me - the term 'Folk' is a reference to origins and source of the songs, so suggesting that it does not matter poses serious problems.

"but deliberately researched a work activity to create 'realistic' songs"
This subject is given a fair amount of attention in the occasionally flawed but otherwise excellent introduction to the traditional ballads 'The Ballad Tree' by Evelyn Kendrick Wells (New York 1950)
In her last chapter, 'The Literary Ballad', she discusses the practice at some length, then gives numerous examples.
For me, her summing up is a superb analysis of the difference between art or commercially produced poetry and that of 'the folk' - an essential hint as to where our songs may have originated.

"The ballad has thus shown itself, even in the few examples here commented upon, as a proving ground for poets. Its stanza and occa¬sional refrain enclose actual ballad stories reworked with new stresses, or popular legends balladed for the first time. From the more pedestrian broadsides unfortunately many early imitations arose, as can be detected by their jog-trot verse. During the Romantic period the medieval ballad, often concerned with the supernatural, held sway, and the “antique patina” was cultivated. The modern poets are hap¬pier than the older ones in the judicious use of commonplace and concrete detail, the challenging “fifth act” beginning, vagueness of time and place, effective dialogue, and approach to climax through incremental repetition. No doubt increasing acquaintance with the ballad of tradition has helped them here; certainly recent imitations approximate the traditional ballad more nearly than the early ones.
The secret powers of ellipsis and allusion are hard to acquire. Rhyme and meter are apt to be unnaturally fluid; but some compensation must be found for that aid to smoothness in traditional verse, the ballad tune, and deliberate roughness would be more regrettable. The ballad’s simplicity of language has led to some confusion be¬tween the trivial and the effective in everyday expression; and in the aping of a dialect unnatural to him the poet becomes, by an ironic turn of the tables, more instead of less literary. But in general, ballad imitation has disciplined the poet in discrimination, imagination, and economy of expression.
It is in objectivity, that veil behind which generations of folk poets have hidden themselves, that the modern imitator fails. He finds it hard to avoid interpretation; a moral, a personal reaction, or a reflection from his own experience slips out. Interest in the emotional and the pathetic lacks control, particularly when it is a motivating cause for the action; the story is not allowed to speak for itself. The supernatural becomes a source of subjective wonder and marvel, made deliberately eerie to evoke horror. The bounds of the simple ballad are thus broken down by the dual interest in action and emotion.
These tendencies are hard to suppress, even if the poet wished to do so. In many cases he does not. The ballad supplies him with an opportunity to speak symbolically in a texture of apparent simplicity. Beneath the spareness, the ellipsis, the paucity of detail, and the plain yet suggestive speech, he may imply his contrasts, comment in parables, harp us up to the throne of God or down to the hinges of Hell. From Wordsworth to Benét the study of the influence of the ballad upon conscious poetry is a chapter in the history of English verse, working in the direction of simplicity, sincerity, and art."

That works for me
Jim Carroll