Its an empire thing. The cultures you mention Fay, are/were at one time, all part of the English speaking British empire, and so share many aspects of culture, like food, religion, dress, etc. But especially the pub, which is where, in the last 30-50 years (depending on where you are) a lot of music gets played.

The Italians and Ukranians don't share those political, social, linguistic and cultural ties, hence their absence from your folk club.