All insurance companies although making vast profits calculate their premiums based on the claims history of the particular item involved. This can change based on lots of issues like location, age of owner and owners previos history etc., etc.
Caravans, to me, seem totally disproportional in cost to repair to other things like homes and cars. I've noticed it on my Bessacrr with a few of the stated costs of warranty work e.g small coffee table & (15" X 5")