This is because WWII was, in particular, an old man's war - almost all the world leaders were in their sixties or even older (hello Marshal Petain !)
These old men had all been young once.
We learn best - and never forget - what we learn around age 15.
So, half a century earlier, all the world's leaders, in every field of endeavor, had all been in high school learning the state of art of Science, as least as high school science teachers understood and taught it.
In 1895, HS teachers understood and taught state of the art science just as the leaders of 1895 Science understood the state of the art as well.
But this happy meeting of minds: from the world's top scientists to the dumbest of 15 year old (unwilling) HS physics student was about to end.
From now on, after 1895, the world's top scientists would have to grapple with new, unexpectedly highly complex, verities to replace Newton's old HS-physics -simple verities.
And if they found these new complicated verities unpalatable, imagine how much more so did the average HS science teacher find them to be.
First to understand, even dimly ; difficult but possible.
Then to demonstrate them physically : virtually impossible, even with the best most expensive university equipment.
Above all to set as exam questions for 15 year old minds, to render forth, inside of two hours, as correctly completed equations.
Simply not possible : the only correct answer any student /teacher/Nobel prize winner can say - thanks to post-1895 Science - is that "the photon is both a wave and a particle and as to where it is and was it it is, at any moment of time, is as good your guess ,teacher, as it is mine."
Not the sort of answers that parents and employers want to hear, nor the sort of answer that science teachers want to produce, if they expect to paid well and much respected.
So,it was not just the old men who ran WWII, but all the young men and women running the actual scientific side of the war, who continued to be taught in, and at least half believe, the old Newtonian verities.
Still are taught them, in fact !
This more than 100 years after they began to be seen, at best, as merely an approximately correct version of a sub section of real physics (IE relativity and quantum physics).
Published Science - in GCR's definition of that term - IE published in peer-reviewed ,credible, journals in basic science, changed greatly, after 1895 ,without really impacting the world at all ---- in the physical sense.
Even its intellectual impact was muted until the 1980s - if even then.
Popular Science ran WWII - which is to say Science as understood by the general population - including Prime Ministers, Presidents and dictators.
And that Popular Science still saw humanity's ability to mold and re-shape Nature and Reality in such exalted, unrealistic, fashion that it led the leaders of the world 1939-1945 into History's most horrific war, simply by extrapolating what they had been taught 50 years earlier in science classes.
To make these distant events seem more pertinent to today (and tomorrow) : the old men running the world today also last learned what little science they know 50 years ago - back before the rise of the environmental science for example.
Inside their perpetually-15-year-old-minds, the remnants of optimistic 1950s-era science still can't understand what this fuss about Climate Change is all about......