As a boy pilot I was told that the direction the rotor turned in the early helicopters depended on the direction of rotation of the crankshaft of the piston engine that they used to power the machine, and that engines developed in Europe and those developed in North America had crankshafts that rotated in opposite directions. Over the years I have seen nothing published to contradict that theory.
Obviously they could have put additional gearing in to change the direction of rotation of the rotor but to do so would have been expensive, added weight and provided something else to fail. Standardization between the various manufacturers does not seem to have been an issue in the early days; or today for that matter.
Rotorbee – OK, you got me, which Eurocopter machine twirls its blades in an unpatriotic manner?