Perhaps it's more complex than that.

I think it's a lot more simple than that actually.

It's an increasing phenomenom where the hall or promoter are trying to shift liability from themselves onto the band. It's probably an amateurish attempt to do so, which wouldn't actually stand up in a court of law if someone was hurt at the event and decided to sue, but the very fact that the attempt is being made shows that the booking organisation aren't prepared to take responsibility for the event they want to organise.

My ceilidh band has public liability insurance, which is only right and proper in these litigious times. If anyone tried to get us to provide risk assessments for an event they were organising, we are lucky enough to have someone in the band who is qualified to do so through his work - but we would of course insist on charging charging the venue his full professional rate to do so. And if they pulled the gig on that basis, that's their loss, not ours.