The civilian mining companies will give you the option to buy their goods, although anything you do not buy ends up (apparently) in the civilian marketplace.
But that's kinda the point - you have an option to buy
all the TN elements depriving the civilian sectors of them. But whether or not any TN minerals end up in civilian hands the money generation (per capita income)
is the same. Which means that the civilian sector is not using TN elements.
Rare earth metals, as well as some platinum group metals such as osmium and iridium are found in very limited quantities on Earth. In all their applications they are used in minute (grams to micrograms) weight. However, they are so effective in their function that they are highly sought after in both military and civilian applications. It is not so bizarre to think that a material that can defy the laws of newton would not find demand in a civilian marketplace. Sorium by itself would be sought after everywhere.
But that was kinda my point. A small recap: The original poster wants to implement the unemployment mechanic. Someone points out that the societies in Aurora are post-scarcity. This is countered by claiming that TN elements make the economy a scarcity based one.
What I tried to do was to point out that TN elements are being used only in very specific industries, relating mainly to military and space travel. However the larger civilian economy is either not using them (which was the first point, about being able to deprive civilians of TN minerals) or using them in such a small amounts that the scarcity is artificial. And if the elements were being used in "minute (grams to micrograms) weight" then having planets with millions of tonnes of them, coupled with recycling, would remove the scarcity. Ergo, existence of TN elements does not prevent societies in Aurora from being post-scarcity ones.
While this is very gamy, I would say that the unemployed people in a highly developed nation (with a well developed service sector) would be able to find work in the service sector with ease. A nation that relies on industry (or worse yet resource extraction) for most of it's GDP would be hard hit from unemployment. A planet with 9 billion people would have a large amount of people outside the TN industry, but there would be plenty of people in the wealth and trade menu making trade goods.
But that's the thing -
Aurora is already simulating that. Currently all people on a planet are part of one of three industries.
Agriculture and Environmental - feeds and houses people. The percentage of people employed in this sector increases with colony cost of a planet. For Earth it's five percent. For a planet with colony cost 2.0 it's 15%. The only exception are orbital habitats which have 0% dedicated to this sector.
Services Industries - The self-regulating, self-supplying civilian sector such as banking, household goods manufacturing, transport, entertainment and other services. The percentage of people employed in this sector rises with the population size and caps at 75% (I don't remember at which point).
Manufacturing - People employed by you or not employed at all. This is the least important part of the economy and as such only people who are not employed in the previous two go here. That means it's entirely possible to have a planet with no one working in manufacturing (for example a large planet with colony cost 5.0 would have well over 25% people in agriculture, the rest in services and no one in manufacturing).
All of the above means that on a well developed, habitable planet you'll have 20% people who are employed by either you or not at all. Which means the larger the population, the more difficult it will be to provide enough buildings/complexes to find them work and more of the new, proposed social structures to appease the poor. Which means that the larger the population, the less viable it will be. Which is why I'm saying that it has to be balanced and why I'm saying that no one is addressing this problem.
This also means that non-habitable planets produce less poverty as larger numbers of people are automatically employed in agriculture and services. Which is counter-intuitive as running infrastructure (keeping everyone alive in a hostile environment) should cost money.
In any case, wealth does not do enough in game so 50% unemployment would not affect the nation in a noticeable way. Maybe if there was social assistance or entertainment funds (like Masters of Orion) that improves happiness, or any government expenditures.
I don't know about you but I'm running into red in my games quite often, even with relatively large populations (over two and a half billion people). As such I'm in no hurry to add more money sinks.