"Communism" the economic system has not been realized. Communist parties have led socialist countries, but communism as a mode of production is a product of the future.
Socialism works, the largest economy on the planet is the PRC, which is seeing rapid and comprehensive improvements in the living standards of its people. Even the USSR, now no longer here, achieved impressive economic growth, provided free healthcare and education, and much more.
Capitalism, by definition, requires that the capitalists be in charge and the workers exploited. It isn't just the US.