I must respectfully, but emphatically, disagree that a group like Calexico, with a synth, a drum kit and contemporary lyrics, is in any sense "folk." They are without a doubt damn good, but if what they are playing is "folk," then anything is "folk." Nor are contemporary singer/songwriters "folk." The list of singer/songwriters who frequently call themselves "folk," but aren’t, is endless. The aforementioned Antje Duvekot, Lucinda Williams, Ani DeFranco, Mary Gauthier, The Avett Brothers, The Stray Birds and on and on and forever. Many are VERY good at what the do (and I’ve seen/heard most of them in concert), but what they do is in no rational sense "folk." (The Birds are "folk" only occasionally these days...) If these people are folk performers, then so is Billy Joel, who is also an itinerant troubadour playing an acoustic instrument and singing songs of his own composition about contemporary, mostly love, concerns. If someone is singing heartfelt pages from their diary, they simply aren’t "folk."
I’ll freely admit to being a curmudgeon concerning the much debated question of what is folk music. The point, however, is not to be dyspeptic, but if the term "folk" is to have any utility at all, it has to have some fairly specific meaning. For me, "folk" means that someone’s music has a significant and identifiable connection to a tradition older or broader than the performer him/herself. After having been deeply involved in the production, promotion and personal enjoyment of "folk music" for well over 40 years, it’s an important issue for me.
This is because misapplying the term "folk" has lead to broad confusion in the public’s mind between authentic tradition-rooted folk music and contemporary singer/songwriters. This in turn has made it difficult for most people to appreciate the profound distinction between the two. It has made it likewise difficult to communicate and promote one kind of music or another to an audience. For example, should a show by Ani DeFranco, "The Little Folksinger" who has never in my experience performed an authentic folksong, and I’ve seen her perform and known her personally for 26 years now, be promoted as the same thing and to the same audience as a performance of English folk ballads by Martin Carthy? No. The term "folk music" should be reserved for those performers whose music has some direct and identifiable link to a tradition older than the performer(s) themselves.
I could go on, I’m afraid, but let me re-emphasize that I appreciate and enjoy music of many genres, including at least the best of the contemporary singer/songwriters. I’m not dissing them in the least. But the lesser ones can be embarrassingly bad and, worse, they are commonly a weedy bunch that will promote themselves aggressively, too often as "folk." This in turn results both in "folk music" getting and maintaining a bad rep, and wonderful and authentic folk performers, who are typically much less assertive, getting sidelined or overlooked. The musical genres aren’t at all the same and shouldn’t be called by the same name.