blindside flank

Question
i have been wondering why most countries and teams prefer a quicker openside flank to a blindside flank. to me its obvious why blindside has to be quicker. his duty is to carry the ball and for that you need him to have speed. were i live (south Africa) everyone knows and accept that blindside has to be quicker and not only blindside but eighthman aswell they are both used as auxiliary centers and break the line in the same manner they do. We put more emphasis on the fitness of the openside so that he can run from one ruck to another on the other side of the field continuously.

Answer
Good question, I agree with you. South Africa has it right and so does Aussie who have run two open siders for a while. NZ has a little differentiation but it isn't much really. The Northern hemisphere countries still have the old fashioned ways and if you ask me that is reflected in their (lack of) success on a consistent basis.