Originally Posted by
Retro Grouch
I think that it has everything to do with standardization.
Most screws and bolts have a right hand thread. If you were developing a new product you'd like to use current standardized parts wherever you could. A screw on bicycle cog or freewheel, with a right hand thread on the right side of the bike will tighten itself as you ride.
But since you have to machine the threads on the cog and hub it's just as easy to machine anti clockwise and put the drive on the left side. It would also tighten as you ride.