I haven't had the pleasure of actually going into an American folk club, or the other places where you can hear live folk music, but I know lots of people who have, and I'm pretty certain that native American traditional song is being sung in such places at least as much as in British folk clubs. Surely just the fact that there are regular exchanges of performers across the Atlantic must tell you this.

Also don't forget there are many more genres of traditional songs in the vastness of North America than there are in our small islands. Those of British origin actually only form a small percentage of this. For instance, Afro American contributions, Cajun, Native Indian, Great Lakes songs, Songs specific to individual states, Civil War songs, War of independence songs, maritime songs from the maritime provinces, Songs of the gold rush, labor songs, chain gangs, the majority of sea shanties, bluegrass, etc. etc. etc.

Laws was published in the 1950s. It only scraped the surface in terms of American traditional song.