China didn't industrialize until after 1978, when they gave up on communism and began a transition to capitalism. Over 30 years after WW2 concluded.
Russia did not industrialize in the 1920s. They did collectivize agriculture, famine ensued. They turned back to free market farming, famine went away. They turned again to collectivization, and farming collapsed again. Eventually, the Soviets allowed farmers to farm small plots and sell what they could raise. These small free market plots kept the country from starving.
Russia did work hard at industrializing during WW2, but it was propped up by the US, who heavily supplied the Soviets. The US actually built factories in the US, dismantled them, and shipped them to the Soviet Union during the war. US engineers and craftsmen taught them.
When WW2 ended, the Soviets looted everything industrial they could find from the Soviet sector. Whole factories were moved east. Soviet industrial output grew during the war.
British industry was also untouched, because the German bomber fleet did not have the range to cover much of Britain, and because Hitler stupidly decided to bomb houses instead of factories. Britain had a pretty anemic recovery from the war - despite getting far more Marshall Plan money than Germany.
Japan did not have a free market before the war, and not much of an industrial economy. Curtis LeMay had a hard time finding industrial targets to bomb, as Japanese industry was characterized as "a drill press in every home". Japan turned to free markets after the war, and we know what happened next. Recall that Japan was burned into ash in WW2. They went from utter defeat to economic superpower, despite not having any natural resources, in just 30 years.
How much more of an "unequal" starting point could there possibly be?
The only common characteristic of prosperity is free markets. And the more free market an economy is, the more prosperous it is. Over and over. It goes back to the middle ages.
The other common characteristic is when countries turn towards socialism, things just get worse and worse for them.
Before opening up in 70s, China had acquired the ability to build by itself: huge numbers of machine guns and grenades, tanks, fighter planes, rockets and satellites (aka missiles), nukes.
These minus nukes and missiles plus battleships is pre-WWII Japan.
This may be helpful if you're curious why so many countries that choose free market instead of Communism after WWII are still not industrialized today.
The difference between the US and smaller countries is that the US government is powerful enough to stop powerful corporations from destroying it by enacting labor laws, environmental protection laws, and anti-monopoly laws with teeth. No other country is advocating for a Soviet style economy. You're fighting a strawman.