I've worked as a contractor for a safety system that turned out to be for a foreign military. I was given a signal, and told to write software to fit it. The signal could plausibly be collected for a wide variety of civilian purposes.

What I realized later was that none of the civilian markets could possibly justify the cost of the project.

The particular type of signal fitting I was doing was only achievable by a few thousand expensive domain experts in the world, so, I think that addresses your other point.