Idling while Hitching up

Should the Club actively advise against this ? I watched this morning at Brown Moor as Caravan after Caravan backed up and then left the engine running while the driver hitched up and fixed electrics etc whilst being less than a foot from inhaling the exhaust ..............TFL etc and other coucils ban this for good reason ....at least 5 vans kept engines running for 5 mins plus during hitch up ..why ?