> There are no maintenance costs for the open sea.

There are massive maintenance costs for the open sea with how we utilize it. Maritime security and policing, navigational infrastructure, weather reporting, radio repeaters, international bureaucracy, etc.

Global maritime trade is extremely costly. It's simply hidden behind opaque public spending on things you don't think about. In all likelihood it's a sunk cost that would ballpark around a few hundred billion dollars annually, invisible money spent just to keep things running at the scale and reliability that they do.

Now the maritime traffic passing through the Strait of Hormuz may only partially overlap with this spending, but people greatly overestimate just how "cheap" maritime activity actually is.