There are likely Free Trade Zones, known as Foreign Trade Zones in the US.
https://en.wikipedia.org/wiki/Free-trade_zone
The idea being to ship in parts, do assembly work in the US, then assuming the finished product does not cross out of the zone but gets shipped out of country, does not pay taxes.
We can probably assume a lot of planets will operate this sort of thing, a local extension of extrality to a degree, capturing employment dollars without lowering tax revenue and/or barriers to destructive internal economy/society wrecking imports.
So the starport and immediate startown beyond may have a large industrial district and attendant population, and a good deal of interstellar cargo coming in and out servicing those industries.
The locals may be assembling and handling much higher TL items then they could afford or the world can support economically, which is fodder for all manner of adventure.
Most of that life support cost for crew and passengers are going to be in the form of supplies, food and services already noted, so even your average Free Trader is going to be spending Cr20000+ per week in port and the larger liners/ship Cr100000+ per trip. Even with a small ship universe and less then 500 ship per week ports, 100 ships spending say an average of Cr60000 each makes for a 6Mcr per week business- plenty of room for services to make bank.
Don't forget services the Travellers, either crew speculators or ship operators do not normally pay or get in the income stream for but would be there too- the cargo handling warehousing and customs work.
We can probably also assume that beyond a certain TL most of these supply companies are going to be operating specialized makers in a starport/FTZ and only 'importing' cheap raw materials from the planet.
C and D starports will of course likely have all sorts of 'unofficial' support services that may- or may not but charge to try anyway- fix your ship or provide fuel at non-standard rates, quality, etc.
We can also likely assume some extralegal warehousing and import/export industries, ones that legally exist in the starport beyond the reach of the planet's FTZ rules but which handle items illegal on the world. They would be the ones looking to circumvent the rules, most likely by raw bribery rather then deception/masking.
Some planets will have 'exports' that will be illegal in the interstellar polity, or trying to export items the world does not want exported or people to escape. There will be 'services' for that too.
Vehicle rental if the adventurers don't have one, for in-port travel and work or world transport.
Don't forget orbital industries- a lot of larger ships that never land requiring the services mentioned coupled with industries that use free solar energy, cheap shipped in-system resources and take advantage of LEO FTZs means a hive of activity at the Up station.
I particularly like the idea of orbital locals venturing between ships in their ratty grav vehicles, peddling food or wares directly like a seaport sampan.
Now if we are talking scifi industry in general not specific to starports, that's a whole nother post.
https://en.wikipedia.org/wiki/Free-trade_zone
The idea being to ship in parts, do assembly work in the US, then assuming the finished product does not cross out of the zone but gets shipped out of country, does not pay taxes.
We can probably assume a lot of planets will operate this sort of thing, a local extension of extrality to a degree, capturing employment dollars without lowering tax revenue and/or barriers to destructive internal economy/society wrecking imports.
So the starport and immediate startown beyond may have a large industrial district and attendant population, and a good deal of interstellar cargo coming in and out servicing those industries.
The locals may be assembling and handling much higher TL items then they could afford or the world can support economically, which is fodder for all manner of adventure.
Most of that life support cost for crew and passengers are going to be in the form of supplies, food and services already noted, so even your average Free Trader is going to be spending Cr20000+ per week in port and the larger liners/ship Cr100000+ per trip. Even with a small ship universe and less then 500 ship per week ports, 100 ships spending say an average of Cr60000 each makes for a 6Mcr per week business- plenty of room for services to make bank.
Don't forget services the Travellers, either crew speculators or ship operators do not normally pay or get in the income stream for but would be there too- the cargo handling warehousing and customs work.
We can probably also assume that beyond a certain TL most of these supply companies are going to be operating specialized makers in a starport/FTZ and only 'importing' cheap raw materials from the planet.
C and D starports will of course likely have all sorts of 'unofficial' support services that may- or may not but charge to try anyway- fix your ship or provide fuel at non-standard rates, quality, etc.
We can also likely assume some extralegal warehousing and import/export industries, ones that legally exist in the starport beyond the reach of the planet's FTZ rules but which handle items illegal on the world. They would be the ones looking to circumvent the rules, most likely by raw bribery rather then deception/masking.
Some planets will have 'exports' that will be illegal in the interstellar polity, or trying to export items the world does not want exported or people to escape. There will be 'services' for that too.
Vehicle rental if the adventurers don't have one, for in-port travel and work or world transport.
Don't forget orbital industries- a lot of larger ships that never land requiring the services mentioned coupled with industries that use free solar energy, cheap shipped in-system resources and take advantage of LEO FTZs means a hive of activity at the Up station.
I particularly like the idea of orbital locals venturing between ships in their ratty grav vehicles, peddling food or wares directly like a seaport sampan.
Now if we are talking scifi industry in general not specific to starports, that's a whole nother post.