CAR: In fairness, you should also mention that the auto industries in those countries are protected by tariff, and foreign imports are extremely limited, thus providing the respective domestic markets with a captive audience, so to speak.
Those same limits aren’t found here in the US.
And, yes, upper management at the Big Three was dreadful, no doubt about it. But pretending that unions were not a motive force as well is choosing to ignore the obvious.
The period between 1945 and 1972 was a historical anomaly. We will likely never see a period like that again, where the US is the single dominant manufacturing power in a world wrecked by a world war.