obviously 'some' singer-songwriter stuff comes closer to traditional styles than does others. There will always be a gray area, and we will have to live with that, but IF you make the effort to understand what made up the music that was called 'folk' or 'trad' when the terms began to be used, you will realized that simply getting 'older' or 'more famous' doesn't automatically confer status in a category.

I claim that "Sha-Boom" or "Blue Suede Shoes" should NEVER be considered 'folk/trad', though they 'may' someday be learned thru oral transmission. Do I have confidence that I will prevail in my narrow view....*grin*....I ain't that foolish!