The same new cars that need the entire transmission replaced if any one thing goes wrong in it? Compared to those poorly built old cars where you could blow a gasket and just put a new one in?
Yes, exactly those. I would recommend reasoning backwards from the longevity statistics to the potential reasons for the changes to the designs of individual parts and systems.
Based on my calculations, it was money.
Sort of. Try looking at the relationship between longevity, resale value, purchase price and margin.