The 5 tons weight per 5 tons volume assumption seems pretty light until you consider that interstellar hauling of bulk materiel is probably not economical.
Why in God's Black Sky would you ever haul 730 tons of pig iron to another star? Don't they have any asteroids?
When you have an entire solar system to use for raw materials, there's just not many reasons to import them.
Finished goods are going to be the profitable items. Low tech worlds make low tech things and import high tech stuff. High tech worlds import low tech goods that because of comparative advantage they can't afford to make themselves.
It means that some really low tech places are going to have iPhones, cell towers and horse drawn transportation... The local TL will mean what they can build for themselves and not necessarily the TL of what's available for purchase.
Luxury goods are always importable and rarely very dense.
Why in God's Black Sky would you ever haul 730 tons of pig iron to another star? Don't they have any asteroids?
When you have an entire solar system to use for raw materials, there's just not many reasons to import them.
Finished goods are going to be the profitable items. Low tech worlds make low tech things and import high tech stuff. High tech worlds import low tech goods that because of comparative advantage they can't afford to make themselves.
It means that some really low tech places are going to have iPhones, cell towers and horse drawn transportation... The local TL will mean what they can build for themselves and not necessarily the TL of what's available for purchase.
Luxury goods are always importable and rarely very dense.