And without incredible demand, there would be no reason to be able to make more, more, more. It's more about meeting competition than just boosting returns. Japan has been kicking our ass for more than 60 years and in the '60s, US automakers had chances to become more efficient and make better products, but they declined. Japan listened and in a short time, they were selling a lot of cars that were higher in quality than what the Big Three could make. Look at UAW wages over the decades- there's no way to make affordable vehicles with so many factory workers making $100K or more.
Don't get me wrong- profit was behind it, but massive profit wouldn't be possible if the goods were made in the Good Ol' US of A.
The techniques to both improve quality and reduce costs were developed in the USA - look up Deming...
US manufacturers weren't interested... he took his work to Japan, and the car companies there, adopted it in full...
Within a few years, their quality went up dramatically, AND their costs went down.
The methods travelled to Europe, to Korea, and only started taking hold in the USA, in the 1990's....
Look at European factory workers, their wages aren't that far off from US worker wages, the cost of labour is not the only ingredient in the mix - and China is not the only point of comparison.