Sure, but why was Tesla able to start up and take a big portion of the EV market over the last few years? The big companies were too slow in reacting to changing demand. It took years to get something that was equivalent to what they are offering...and yet they still don't have anything close despite far more industry knowledge on how to mass manufacture cars.

There are economies of scale. There are also diseconomies of scale:

https://en.wikipedia.org/wiki/Diseconomies_of_scale

Inertia and institutional sclerosis are serious problems for organizations that are large, old, or both.