@gnuconsulting Lobsang’s blimp makes that clear, it is possible to move technology across the worlds. In the later books they have an entire airborne transit system for moving people and cargo. It’s only iron that can’t be carried, other metals are fine.
Plus, they had geographical survey data of where all the resources are, resources fully unplundered and even surface level. Yea the early colonies have a hard setup process, but iron is easy to forge when hydrocarbons are plentiful.