Hi jag,
I wouldn't exactly call it financial gain although it plays a secondary part in that people like Scott wanted to make a name for themselves and needed to sell books to maintain their status in society. Patronage also came into it. Certainly Scott and Buchan had the patronage of powerful people. It is pretty obvious that Buchan was trying to emulate Scott and he went to great lengths to try and sell his manuscripts, but he was suffering financially at the time as was Scott occasionally in trying to keep Abbotsford running, quite a substantial country residence. In Scott's case I don't think you can use the word fraud or even mischief. He was following in the footsteps of Percy. unfortunately those that came after Scott and Jamieson were competing for sales with already well-established ballad editors and Buchan went way over the top in what he claimed. The biggest motivation especially in the 18th century was linked to the need of literary Scots to establish their separate identity from their southern powerful neighbours.

There are certainly new songs around now that pass for trad but as far as I know none of their authors have tried to pass them off as trad. If anyone took one of my songs for trad I would take that as a massive compliment. 'Bring us a Barrel', 'Shoals of Herring' and 'Fiddlers Green' spring to mind.