Exactly. And this is true for a lot of industries. Developers seem to have the impression that only software is a bit "messy", but that's because we're looking from the inside.
People wonder why large construction projects are often delayed. Well, it's often for the same reason it happens with large software projects.
You're 100% right. This it's the exact same reason why the writers strike affect something that I theory should have not effect as the shooting or editing of a movie.
In my experience media production only follows the waterfall model in paper or a really small projects, in practice it's like a chaotic version of Scrum/kanban with no standard that changes from production to production.
People wonder why large construction projects are often delayed. Well, it's often for the same reason it happens with large software projects.