If they're still in hair on fire mode after having many years and multiple previous models to practice on before the Model 3, that's the part that makes me think they don't grasp it.

Elon's software background, plus SpaceX which is fundamentally a very different kind of manufacturing, probably works against him here. Software startups essentially hate process (for often-good reasons) and view process as mostly a thing you put into place out of necessity after you've successfully navigated the growth phase. The stories from their production floor are the single most worrying thing that's come out about Tesla - bad vendor quality control, overengineering a la the Model X, all those other things are comparatively simple to grasp, learn from, and overcome. Why wasn't "learn how to mass-manufacture reliably" a much earlier goal?

Just because a system took 27 years to develop doesn't mean it takes 27 years to learn.