The basic idea of the mixed economy is that the means of production are mainly under private ownership; that markets remain the dominant form of economic coordination; and that profit-seeking enterprises and the accumulation of capital remain the fundamental driving force behind economic activity.Governments in mixed economies often provide environmental protection, maintenance of employment standards, a standardized welfare system, and maintenance of competition.Also because our economic system is capitalism.
So just put all those together. Government limited control , we have capitalist economic system & that s why it s best match for the U.S.