And if the US had been the one to capitulate to communism we'd be quoting stats about the lack of income growth of their workers in contrast to the wealthy.

Viewing the health of a nation on the growth of their income isn't necessarily telling the story. Soviet inflation was almost unheard of save for hyperinflation shortly after the revolution, and hyper inflation after the collapse. Also as investment wasn't as much of a driving force since the economy wasn't private, so infinite growth isn't necessarily a good indicator of the state of things.