That doesn’t surprise me. Think about it - it would be weird if Toyota instantaneously created a great, dominating product in a sector of business with an enormous capital investment bar to entry. It would be impossible for them to get to where they were in the 90s in 2 years. It takes time.
It would make more sense for it to grow into that.
My off the cuff (but I think reasonable) guess is Toyota was improving component manufacturing but struggling on full assembly. Engines and trans improved but all the smaller supporting items and systems snd third party and business logistics supply side of automotive assembly for a final product took longer.
In the 70s people were requesting Japanese (Toyota I think) transmissions and Ford was scratching their head. It’s not advantageous for their supply line to have more demand for one part supplier making the same part. They want demand on a vehicle model, not specific part within a model - it’s so half sell and half sit (I’m exaggerating that of course). On the street, with consumers, they were widely known as better. Ford Higher ups scratched their heads because all of their specs to any trans builder were identical. In the end they found the Japanese manufacturers had tighter tolerances/less variations which resulted in fewer issues.
They went from “This spec works” to “what failure modes are happening and how can better processes and specs address them”?
Welcome to Toyota 2021