The young performer must preferably not perform his or her own original material, but if she/he does deviate from traditional repertory, it must resemble a ballad about cow farming, ploughing, sailing, or other such traditional subject matter about which the performer will invariably know nothing about

No idea where you're getting all this from. There's a club I know where the same faces line the walls week in, week out, and some nights I lower the average age by going in (and I'm 51); but you'll never hear a traditional song there, and it's a job to get anyone to join in on a chorus. There's another where the same regular audiences face the same regular performers, give or take a few, week after week after week; but given that half the regular performers are twenty-something singer-songwriters, that's probably not the kind of place you're complaining about. Then there's a singaround, where traditional songs reign and the choruses can get a bit slow; that's obviously not the kind of place you're thinking of either, as anyone under 30, new or both is welcomed with open arms and much applause.

In short, I think 'folk club' covers a huge range of different types of club, and you're combining all the worst aspects of lots of different clubs without including any of the good aspects. Your folk club sounds horrible, but I suspect you've only been there in your imagination.