Surely the old Ford assembly line would do anything one needed. The answer is geography. Simple geography has changed the course of factory layout. While Americans have wide, open spaces in which to build, the Japanese do not. They have a little island that is stacked high with people.
Space is at a premium.
In order to build a factory with the volume capabilities of those in the United States, the Japanese would have to utilize all of their space. They would have to come up with ways to make processes shorter so that fewer machines could be used so that fewer workers would have to be employed. They would have to develop extremely efficient groups that save time. The problem for the Americans was that the Japanese managed to do this very well. This is now a time of competitive, cutthroat business.