It's only a fluke because we've allowed the resources that once enabled this period to accumulate at the top so that it's not feasible on a broad scale any more.
It was a fluke because the US was unscathed by a war that destroyed much of the industrial and productive capacity in the rest of the world, at the same time vast strides in technology were being made. The US worker had a worldwide monopoly on labor and innovation for 30 years.
This explanation seems lacking to me. The same time period had a single-earner home-owning, baby-boom-raising middle class in places like Germany and Japan where entire cities had been completely obliterated by war. They didn't have as many cars or televisions as the Americans but they could pay their mortgage. And blowing up a whole bunch of productive infrastructure and capital worldwide is not the kind of thing you'd expect to contribute to gross material wealth. And gross wealth should be much higher now anyways, since we have so much more technology and better infrastructure.
The only reasonable explanation I can see is a distribution-of-wealth lens. Workers clearly had much more bargaining power during that era, but why? Is it because so many men were killed during the war? Because women who had been working in factories were expected to become stay-at-home mothers? Because of insufficient automation?
Because all accumulated wealth was destroyed. The playing field was leveled by bombing it. That's why it's a fluke, an anomaly, it took years of worldwide destruction. No spring without winter.
As much as I’d like to agree with this, India was literally in the trenches of its own civil war and independence movement AND impacted by the world wars AND figuring itself out as a new country in the early 50s.
Yet Indian middle class was still very distinctly one-income driven.
