I asked this question many years ago and my POF instructor postulated thus:
The very early experimental helicopters had two rotors on booms to the left and right of the fuselage, because they were contra-rotating there was no requirement for a tail rotor.
When the aircraft were broken up after the test programmes, one set of rotors went to the USA for further research and one set stayed in UK/Europe. From that move any helicopter developed in the States had rotors rotating counter-clockwise when veiwed from the top and in Europe they went the other way.
But, I hear you ask, why do Wastelands aircraft have the SPAM direction of rotation? Because they started off producing Sikorsky aircraft under licence and just carried on the motion.
It seemed like a fair explanation at the time but I'm always open to other guesses.
Wiz