Now we have the factory mode, and it looks great.
But seems we have to build a workshop for each platfrom of car (or engine) , and the smaller one is less effective.
For some company who build variety of car at small quantity (like some super car, they hardly share same platform), it would be better to have a Flexible Manufacturing System (FMS).
The FMS factory would cost more money to construct and run, and even be less effective at same scale, but it could turns out to be a better choice for a company who build cars with variety of platform, compare to build multiple smaller workshops.
In reality there are several different approaches, yes. In Automation we are going to stick with the concept we have chosen because it makes it a lot easier to handle from both a user point of view (less confusing) and a programming and maintenance point of view (complexity). We think this is the right choice, gameplay over realism in this matter.