I read about so colled 'shunts'. Steelplates you put into the earth to protect your construction site for water. It is also partial used on a river side.
Those things are not painted and google told me that you can calculate how much is oxidized in a year.
I would really love to know how a shipping container is so much more fragile.
Perhaps it is not that relevant but in masses it makes a relevant amount of money. Like steel container 20 years and with color 25 years and that makes it just better.
You're right. There isn't. It's taken for granted that you are aware of the fate of unpainted steel in a salt air environment.