Have never been to the UK so have no idea what the "folk culture" is there. Also don't have much of a handle on what might be meant by "folk culture" here in the USA. Also not sure if this is about communal or informal singing or performance singing as occurs even in song circles. My impression, which may be incorrect, is there is a tradition of communal singing, at least on the choruses, in pubs in the UK and Ireland that has never found a foothold in what is now the USA. Don't know if it found a foothold in Canada or not.

Communal public singing in the USA has always been present, but happened more in churches and/or southern fields arising out of African traditions of work songs and field hollers. Or, as Hoot noted, on front porches. Has always been singing and playing on the back porch throughout the central and southern Appalachians. Our large land mass has made for a much different experience in the USA. In New England and what is often referred to as the Atlantic Seaboard (from perhaps Philadelphia and north, where geography and topography fostered villages and people living in close proximity relative to points south and and west,) there may be something approaching a pub tradition of singing and choruses, but I base that purely on what I have read, learned and perhaps incorrectly assumed from reading posts above the line on Mudcat over the past many years.   

After typing all of this, which I will let stand, fwiw, I realize I don't really understand what your experience was in the UK, nor what your experience has been here on the other side of the pond. I also don't know what you mean by folk culture.

As has been demonstrated 'in this town many times before' folks can fight all day and all night about "what is folk." I have no interest in that debate and suspect you don't have a dog in that fight either. Just wondering what it is that you experience as different within your own personal context between your experiences in the UK and your experiences here. It sounds like whatever you experienced in the UK was good and satisfying in your experience in a way that you have not found on this side of the pond.