Let's face it ... in this litigious society of ours, ANYONE will sue ANYONE ELSE for ANYTHING, and they will find a lawyer to take the case ...
In the musician's case, forget the 'tripping on a cable' (I always try to make sure mine lead behind me or they are covered with duct tape), as hellboy said, if someone is dancing to your music and falls, you stand as much chance (maybe MORE) of getting sued as the venue does, whether it's a club, NH, whatever ...
You may not NEED the insurance to work in a particular place, but you may WANT it, no matter where you work ...
... AND no, I do not have it ...
t.