Bottom line appears to be it depends on the show organisers and/or the venue, but it's certainly not universal.
In any case, that *could* be funded by a small levy on the show stand admission fee anyway.
In principle, it's arguable that members who have no interest in "showing" their own cars shouldn't really have to pay insurance for
those few who do, but obviously that's just one viewpoint and open for debate.
A counter argument would be that the club might lose its "show presence" altogether if stand costs had to be subsidised by an entry
fee.
Nevertheless, there are often two (or more) sides to issues like this and there's nothing wrong with debating these sort of things,
even if the new "commitee" ultimately decides things should stay as they are.
Sid