There is a huge difference between the US accounting for 20% of Global GDP and merely being "in first place" at the end of WWI and the USA having half of global GDP (and 80% of the world's hard currency reserves) at the end of WW2. While also say, having a Navy easily more powerful than the rest of the world combined, and being able to to focus on an upcoming surge in consumer consumption as opposed to desperately struggling to stabilize food production and rebuild cities and industries that had been ravaged by war.

Britain, a victor that had never been occupied, wasn't able to lift many significant food rationing schemes until the 1950s. Bread, which wasn't rationed during the war, had to be rationed from '46 to '48.

There is a meaningful distinction between being the leading industrial power and being the overwhelmingly dominant economic power.