That quite easily could be straining the cargo capacity the subsector has available, and any increase in population increases the risk that a disruption in shipping results in mass starvation.
Beyond the obvious answer that these are more of the truckloads of odd results you'll get as the result of a random die roll based generation system that hasn't had enough influence of the "realism police" to more aggressively eliminate the large number of unlikely outliers, there's a number of solutions:
* Perhaps at any given time, the overwhelming population of the world is literally hooked up into a Matrix-like system where from birth to death everyone spends their life in a pod fed nutrients directly into their blood. Only those with critical maintenance or security roles, as well as jobs that require travel are not hooked up to it. This isn't considered slavery or creepy by the world's inhabitants, it's considered a good lifestyle. I have no idea what they do for a "living" (or perhaps they don't have jobs or whatever as their living expenses are so low and paid for by the state).
* Assuming these population increases were reasonably predictable, another world may have a complex series of literally tens of thousands of huge disc-shaped agricultural habitats close to their local star (as well as using artificial lighting closer to home). A significant portion of the population is devoted to transporting inputs to these habitats and transporting outputs to their homeworld. The process of building such an infrastructure might seem like a ludicrous expense, but if this population growth has been going on for decades or centuries, this infrastructure would have been built up over a similar period of time, so ongoing costs of expansion and maintenance are amortized as inhabitants refine their systems.
* A world may have engineered chemosynthetic bacteria that can be refined to produce nutrition for humans. These extremomphiles have low productivity, but essentially every single one of the system's "barren airless moons" in orbit around gas giants are essentially huge farms of for this stuff, utilizing geothermal heat from gravitational stress which keeps underground water liquid. The water and geologic grinding action liberates nutrients from the rocks, which the bacteria use for food. The bacteria are harvested and refined into human-usable nutrients and transported to the world.
* Entire efficiencies of food production we can't even imagine might occur on some of these worlds, driven by simple need, without resorting to synthesized foodstuffs but foodstuffs that a 21st century person would be familiar with. Cheap, compact, fusion power makes all kinds of things possible. Fast-growing foodstuffs, laws that require every large apartment building to be self-sufficient for basic nutrition, aggressively recycling programs combined with mining and refining infrastructure strip-mining moons to make up for losses of resources. Given how these kinds of things turn out, at least one of the worlds would be a net exporter of high quality luxury foodstuffs to neighboring systems even while nobody goes hungry on their world, something that is widely discussed and studied in the Imperium (even moreso because nobody else has ever been able to achieve the same results).
Another point is that all of these worlds are going to be like an industrial Japan's resource situation: Traveller has some (rather quaint now) assumptions about some blithely capitalist future involving interworld trade, without touching those assumptions, we can infer some things. Since these worlds can maintain these populations (you don't have large starving slums on such worlds - they couldn't afford that kind of entropy, even 0,000001% would be a huge number of people - there's not enough space for it). That means the large population is very productive in various economic areas. There is simply NO way a world like that is going to be able to fuel its own industries by the resources on its world and likely even in their own system while exporting products. So even without the specter of starvation, they require a massive fleet of starships simply to transport raw materials for use by the planet's inhabitants to keep their economic engine greased.
The economic productivity of such a world cannot be underestimated. The number of ideas generated by a population that size and with the easy access to workers means ever-increasing benefits of economies of scale. These worlds are going to be the Shenzens of their local area, basically forcing many worlds around into agricultural and resource supplier subservience simply because they cannot hope to compete with such a concentration of talent and industry.
If you thought the population situation was bad there, you have to imagine such a prosperous world is likely to be a magnet attracting all kinds of immigration from surrounding worlds, perhaps as far afield as a subsector. These worlds are far from the overpopulated dystopias you'd first imagine. They're glittering, wealthy, fashionable places to be, bursting with opportunity - people want to go there. Sure they might have to deal with laws that are considered oppressive to keep the population in order, but it's likely there's still enough distraction and freedoms to keep the population content. If they were anything short, they couldn't maintain their populations; there'd be conflict and conflict would quickly result in mass exodus, wars, and starvation. So these worlds have obviously avoided these situations, which would make them productive by default. It'd be a huge headache for a sector Duke to prevent or at least slow such immigration to such a world without being a tyrannical oppressor of some stripe.
:devil:
