Apologies if the informnation is already out there on this one, but from my memory (distant) early helicopters had a single collective lever in the centre and two cyclics. The left seat pilot had to fly with his right hand on the collective and left hand on the cyclic. As most(?) pilots were/are predominantly right handed, it was easier and probably safer to have the captain/solo pilot in the right seat. Having flown fixed wing as well and got used to flying from the left seat with right hand on the throttles and left on the stick, I've always wondered whether it would be easy to fly this way round in the hover. Not tried it but I'm sure someneo out there has!