But why did the IN build the depot in an inhabited system in the first place? With the local TL lower than 15, they get little help with the primary purpose (nor the other purposes) and civilians complicate the problem of security that is stressed in the canonical description as being of great importance.
To me it's an explanation that introduces new questions.
Hans
Services not provided by the military.
Recreation, from sex workers, to eateries, tailors, sporting equipment rentals, etc. A military person needs to distance themselves occasionally from being surrounded by nothing but military.
Sex workers are self explanatory and a touchy subject. Suffice it to say that playing where you work is never a good idea.
The US Army for example has a 14 day menu. That gets old quick and off duty personnel hit all variety of local establishments from fast food to ethnic gourmet.
Every large military base has shops devoted to sewing insignia on, and maintaining, uniforms. Add in shoe shine and quarters cleaning for NCO's and officers etc.
Any upwardly mobile military officer, and senior NCOs, will avail themselves of tailored uniforms if affordable and possible.
Rentals are available through base recreation but are limited in quantity, availability and type. Surfboards, boats, scuba equipment, bicycles, 4 wheeling, RVs, electronics, you name it.
Civilian contact is essential for military personnel far from home for long periods of time. Religious needs, the pretty girl at the ice cream shoppe, shopkeepers, bartenders and waitresses, etc.
In many cases a lower TL is going to work to advantage in both willingness of indigenous domestic labor and currency exchange rates.
Security at the unit level is a tough one, but in depots, those civilians wouldn't need to get near ships. Offices are quite another matter... Security would still be a tough situation no matter what. Military personnel can be corrupted as well as indigenous people.
I think it would be hard for a person having no military background to fathom. Additionally, a small "stay at home military" isn't going to go through the social and ethnic deprivations that a long term, distantly deployed, away from home military will of necessity undergo. Anyone from the "local military" mindset is going to have a hard time with understanding the hardships too, as they were almost always stationed close to home.
Hard to give better examples without transgressing the social and political rules of CotI. A
few examples might be the difference between the German "High Seas Fleet" before and during the WW1 era and the US Navy Asiatic fleet and "China Marines" before WW2. The German Fleet was home ported never away from home long. The US Navy and Marines were half way around the globe for years on end.
The movie "The Sand Pebbles" gives a good idea of what this was, and might be, like.
the Darrian Confederation.
. (No offense, it's just I've got a kid in college and money is tight.) The decision to make all depots captive governments suggests the Imperium isn't just buying up huge chunks of real estate from the locals - they're taking active control of the primary world itself. It's not entirely clear the local population is anything but Imperial Navy, contractors, and civilian businesses and employees actively supporting the Imperial installation, but the revised Depot populations range from the tens of thousands to the hundreds of millions. Some of those depot populations are so small that they're either ALL navy and related or have rather large populations of uncounted folk, while some of them have so many people that it's difficult to believe all or even most of them are working directly or indirectly for the Navy. 
