But if America is anything it is a nation of businesses. Are you advocating that America should withdraw into its shell?
America created the international system after the Second World War because She was confident of being competitive. What do you think America gains from withdrawing from two continents?
Yes, it is. China, on the other hand, is more of a fascist state. American businesses are not interested in risking capital investment in places, such as Africa, where tribal violence and civil wars are all too common. China, on the other hand, will have no problem defending its investments with the PLA in one guise or another.
As for South America, there are a number of American business interests and investments including American investment in some companies. That said, there are some areas of South America where American companies are not keen to do business because American businesses, in the past, were chased out of the nation (usually by communist/nationalist movements).