When I read the title, I groaned. Since when is painstakingly correct grammar expected in folksong?

But then I read the first two posts, and agreed completely that those particular examples are cringeworthily awful. Of course, those examples are contemporary (or, at least, recently written) songs ~ not authentically traditional lyrics voicing the informal speech of real people. Nor even plausible down-home diction created by a modern lyricist (like Dylan's "I never knowed," which always seemed OK-enough to me).

"The world in which we live in" has always bugged the hell out of me, too. Amos' suggestion that McCartney is "really" singing "in which we're living" doesn't hold water, much as I wish it did. Even allowing for differences of dialect, the requisite "R" sound just isn't there in his recording. Now, if I were ever to sing this song, I would "adapt" it by using Amos' brilliant little revision. Too bad Paul didn't think of it before he published and recorded. (Since it was a movie theme, perhaps he was working under undue deadline pressure...?)

And as for believing that "you and I" is always correct, and "you and me" always wrong? I've encountered that myself; it's the kind of phony snobbery also seen when people use big words without knowing their actual meaning. If our friend's schoolteacher actually taught him that (i.e., if it was not a misunderstanding on his part), it's a real shame, especially since no subsequent instructor ever set him straight (until the above explanations emerged on this thread). Just goes to prove that even in New England, ignorance is not unknown. (Of course, it may be that, in New England, there is undue societal pressure to pretend that one is more erudite than is actually the case.)