We seem to be back where we started.

I don't know how you can tell from the BBC listings whether sessions in the UK are held in expensive venues or cheap ones. You'd find they're held in all types of venues, from expensive hotels to basic pubs.

I will agree with you on one thing: organisers probably do want to lock out those who are there for an evening of drinking and song - they tend to make an unpleasant audience themselves and spoil the occasion for others. Anyone who is there primarily for the music will find the price of drinks to be less of a factor.