exactly the same criteria that made the other stuff Traditional Folk Music / Song

Again, this is just a statement of faith - I mean, exactly the same criteria? What are the chances of exactly the same criteria continuing to apply from, say, 1859 to now? Of course, you can decide beforehand that those criteria have got to continue to apply, and you can define them loosely enough to make it believable. But if you do that - if you include situations where there's no oral transmission; where songs and tunes aren't being shared within a community which pre-exists the music, and altered in the sharing - then we're just going to have to develop a more tightly-defined set of criteria for situations where those things are happening.

Folk art forms are great, and there are a lot of them about - no argument there. But it takes a very specific set of circumstances to produce folk songs, and it doesn't happen much any more.