Some would say the major asymmetry is that the United States is a developed economy, while China is a developing economy. China has been able to develop by attracting foreign investment, based on its low wages and good infrastructure. However, China doesn't want to get stuck in this low stage of development, and wants to actually develop domestic companies that can compete internationally. Completely opening up the internal market is not necessarily a good way to achieve that goal. Most developed countries got to where they are now with the aid of protectionist policies. Toyota wouldn't exist if Japan had completely opened its market. GM, Ford and Chrysler would have strangled Toyota in the bathtub.