It has too be leftovers from changed plans and designs by CA. They did have plenty of changes and unfinished ideas as they created this game, and the traces of that are all over the files. I think this is one of them, and one that they also forgot about. It has happened to me many times as I worked on Redux over the years, its easily done.

Anyhow, you can't (naturally) build that stuff without tradable goods and the same is also required for the building to generate income... If memory serves...

- A