Caravan wheels to torque or not to torque ?

rubberman

Having returned to touring after a 12 year break I am perplexed by the reports of wheels coming off caravans. Why is it necessary as suggested to regularly check torque settings this is not required on a car or suggested. Surely if wheels can come loose
then there must be a design fault if the nuts were tight to start with, or is there something different in the design of caravan wheel design ?