Folk clubs are just that – clubs.
People have 'clubbed' together to sing & play songs they all love. So it is natural that they expect to join in & sing together.
A concert is a different situation & I find that audiences at such events don't join in unless invited.
In a club, if I sing an unfamiliar (to the audience) song & over a period of time the audience start joining in, then I know they have listened & enjoyed the song.
Very gratifying.
The occasional 'egotist' who has to show off can always be silenced by pausing & asking if they mind listening to your version!

As for the differences between cultures – a well known Canadian singer appeared at my local club recently & said it was great to hear everybody joining in because 'back in Canada people sit like dummys'. (his words, NOT mine).