Tow bar weight limit

On our travels I sometimes see on service area’s couples sat eating a meal at the table in their caravan, with the caravan still attached to the car without the jockey wheel or corner steadies down to take the weight off the tow bar. As the combined weight of the couple would normally be twice the recommended weight limit of the tow ball, this is in addition to the normal running weight, is this not putting serious stress on the towing gear, and what could the consequences be?