Correction 1: many people who attend(ed) Scots Music Group got the dots for Ashokan Farewell from one of their tutors’ books. Nigel Gatherer sought permission from Jay Ungar to publish the score before printing it in said book. So they will know it is not a Scottish tune.
Correction 2: “some” or even “a few” (not “a lot”) of people have not memorised the tune in 40 years, but vast numbers have. I, for one, have been playing it from memory for years: the only time I use the dots is when playing the very nice harmony part that another tutor wrote.