"but they are a singing tradition."
This is true Brian - the operative word being A rather THE singing tradition (if you count them as singing, that is - many are tuneless chants).
I think it is as Bert Lloyd said at the end of Folk Song in England (will have to paraphrase at this hour of night) "If The Red Flag" and 'Little Boxes" are folksongs, then we will have to find a new name for "As I Roved Out" and "Banks of Sweet Primroses" (wildly inaccurate examples).
The context, function, disciplines, styles, relationships to the singers, etc, are entirely different to the body of song that we have, up to now, referred to as traditional song.
You have made the point that we don't necessarily want to sit through 'Happy Birthday To You' or 'You'll Never Walk Alone' in our clubs; so where do they lie in our understanding of traditional songs?
In the field of research, they surely lie more within the scope of custom or ritual, rather than alongside the creative observation that has gone into the making of our traditional songs?
The childrens' songs, I believe are a litle more complicated, dividing themselves into two distinct sections, funnctional - ball-bouncing, skipping, etc, and parodies. I wonder if kids are still re-making songs as they once did with The Cruel Mother and Lord Randal - anybody know?
Jim Carroll