I am from the UK and as two other UK posters have said, RUS is not widely known here - or at least it is just one of many song books available.

It is not common in the UK to see published books at singarounds (which seem to our equivalent of your song circles) but personal song folders are common. I have come across some very good singers who feel the need to have the words to hand and I would rather hear them sing than be rigid about whether or not the words should be learnt.