Well, I suppose that there is a "Current Tradition" generally recognized in UK folk clubs, but isn't there another, wider "Current Tradition" that exists in the contemporary world at large?

My point of view for this discussion is that of a busker or streetsinger. (Disclaimer: I am not a currently active street performer, but I do have a great deal of long-ago experience in that line of "work.") The honorable occupation of troubador should certainly be included included in most conceptions of a folk-music community.

The "community" whose "lore and customs" must be well-known to the street entertainer is the general public, and specifically, the contemporary public whose collective lifetimes have been spent exposed to mass media in our "shrinking," ever more homogeneous world.

Now, no one would expect every passerby to recognize every selection in a performer's repertoire, so there is certainly room for the unexpected, the obscure, the new, the really old, etc. And also, of course, any decent performer should have an identity and personality that would include a bent toward certain general styles or subgenres of music, more-or-less to the exclusion of others.

But:

People respond to what's familiar to them, and want to share the singer's enjoyment of songs known to all. In the world that we really live in, the shared musical tradition is NOT that of a rural outpost in bygone days.

Our shared tradition includes plenty of "real folk songs," such as many of those submitted to the recent "Fifty Songs Everyone Should Know" thread, but it ALSO includes:

Beatles songs
"Over the Rainbow" and other such movie-musical (and B'wy) classics
Doo-Wop oldies
Commercial-country Nashville compositions from the Carter Family through Jimmie Rodgers and Hank Williams, Johnny Cash and (maybe even) beyond.
Pre-war pop "standards," especially those commonly used for jazz improvisation via fake-book transcriptions: Gershwin, Cole Porter, et. al.
Dylan!
Rock, "singer-songwriter" stuff, etc. ~ any individual song that has made a wide impression and become memorable to the general public.

Anything, in short, that the performer enjoys enough to learn, and to work up an effective interpretation.