Facilities are part of the equation. But people have to be trained and measured and certified. Those processes have to be designed and documented. The population needed for any process varies with the task - it'd be a coincidence if it was the same for a different pipeline.

And the facility is full of jigs and benches and tools and doorways and props and a million things that are bespoke to a process too.

Making very complicated things isn't the same as making toasters.

I get its terrifying complexity here - and lots of it is bespoke (and international, but outsourced parts probably helps in this case as it becomes someone else’s problem). But when e.g a car manufacturer makes 2 new models they try to keep many components similar. Planes aren’t cars but you’d think at least some systems are common to both A350 and A380.

The pipeline is pretty much bespoke, but they could move machine tools, people and buildings over to a different project if this project ends. I suspect that's why they are pressuring Emirates into committing to furter orders several years out. Had those orders not materialized, Airbus would probably have planned other uses for their existing resources. They are increasing production of all of their other products after all.