why is 45% of america's auto market foreign if us productivity is superior?

even without unions and superior productivity, usa workers are unable to compete with labourers making $250 a month in china (a country that has much stronger productivity growth than the usa)...as i said earlier, japan and especially japan's auto industry isn't a good example because it has the highest wages in asia...most of the rest of asia's low wages overcompensate for their lower productivity