It became required switching off material about 2 years ago, when they decided that lap steel went with every bloody song.
Then again Jerry Douglas is credited at the beginning, and it is aimed at selling loads of copies of the CD's. Then there's the fact that there are more Americans than Brits to sell to. Somewhere in there you'll find the answer.
I mean, when I listen to American folk radio, I hear very little that I would consider as folk, and TS fits that bill, and judging by last week's selection, Mike Harding's programme is heading the same way.