Do you mean to say that two non-dependant tasks in an Airflow DAG aren't able to concurrently execute? Thats not my experience. I'm also confused by the use of 'static' in this context.
That's the point: non-dependant tasks can run concurrently in Airflow. In sh/BAsh/dgsh dependant tasks can also run concurrently, as in tar cf - . | xz.