|Harder to grow than you might think
The review of the Amber Zone "Foodrunner" caused me to think about the need for food in the Far Future. Eating, on a regular basis, is and always has been the major occupation of mankind. Barring any sci-fi alterations to our biology (which would change what it means to be human) the need for food will still be of major importance in the future. It is as simple as supply and demand, as I will now demonstrate:
Demand: Everyone eats. Everyone needs to eat regularly, as in every day, and everyone needs to eat a certain quantity of food every day. This demand is constant. There are, by current count, 11 TRILLION people living in My TU. At 3kg per person per day (not a scientifically rigorous figure, but it is reasonable), this is 33 BILLION TONS of food consumed PER DAY. That's a lot of food. Certainly, some people or worlds are going to get more than that bare minimum share, while others will get less. But it averages out, for the level of granularity I'm working with here. Humans need between 2.7 and 3.7 liters of water per day to avoid dehydration and its attendant ills. (1)
As an example most folk will find familiar, take the planet Coruscant, from the Star Wars prequel trilogy. The Wookiepedia claims that this world has not a Billion, but a Trillion inhabitants, and that the planet's surface is one continuous city. Going with the basic human standards I mentioned above, they need to generate 3 billion tons of food and 4.07x10^14 liters (407,000,000,000,000) of water per day. Every day.
Now, on to the Supply side of the discussion.
1) Limit to Supply: Humans have definite biological tolerances, which cannot be exceeded. Our bodies need certain things and need to avoid certain other things to go on living. As such food, in order to be food, must be within those biological tolerances.
2) Limit to Supply: Flora and fauna are directly related (on a chemical level) to the soil [i.e. planet] they come from. This affects how well they meet condition one, above. Humans IMTU live on some very un-earth-like planets, that by the fact of their planetary chemistry (a lot of planets have 'tainted' atmospheres) are not going to produce human food without some serious modification. Which means it costs more money to grow food on that world. The more it costs to grow something, the less of it there is, or the harder it is to acquire.
3) Limit to Supply: Even on more Earth-like planets, there are places where it is difficult to grow food (too cold, too hot, too wet, too dry, not enough soil). The United States, one of the major food producers on Earth, has only 16.9% of it's land area classed as arable land, and 4.9% of our imports are agricultural products - food. (2) Humans are limited in where the food will grow, and face added cost in making food grow in less-than-optimum locations.
4) Limit to Supply: All modifications to make flora & fauna edible will cost money, which takes away from other sectors of the economy, so it may not be profitable to raise food everywhere. The more assistance the food needs to grow, the more workers are going to be necessary, which takes labor away from other areas of the economy. Artificially grown food (hydroponics) and chemically derived foodstuffs ('food concentrates' 'food cubes') have their own expenses, for the raw materials and infrastructure but this may be able to be overcome by bulk production. Furthermore, food must be transported, and while bulk transport is relatively inexpensive, transport costs do add up, especially over multiple jumps.
By comparison, hydrogen, the fuel of choice for fusion power generation in Traveller, is extremely plentiful throughout MTU. In fact, it is the most common element in the known universe. While it may not be super-accurate to assert this in the real world, in Traveller, all Jovian or Gas Giant planets are big balls of hydrogen which is free for the scooping. Hydrogen fusion is introduced at TL 9, which most all of the planets IMTU have reached. Therefore, fusion power will be plentiful and will be reasonably cheap, unless artificially restrained. Petroleum should be fairly common as well; any planet of say size 4+, hydro 4+ and atmosphere thin or better will have plant life that can eventually become petroleum.
To conclude, the planets with the favorable conditions of soil, atmosphere, hydrosphere, population and technology will be planets that have power. They have what everybody needs - food. While some Traveller players look at which planets have TL-15 and Industrial trade classifications, I look for the planets with the Agricultural trade code.
1) Sawka, M. N., Cheuvront, S. N., & Carter,Robert, I.,II. (2005). Human water needs. Nutrition Reviews, 63(6), S30-9. Retrieved from http://search.proquest.com/docview/212334059?accountid=12085
2) (CIA World Fact book)
For further reading:
Feeding Frenzy: the new politics of Food https://books.google.com/books?isbn=1847658792
Full Planet, Empty Plates: the new geopolitics of food scarcity
Food Politics: what everyone needs to know