I could list dozens more sectors of the software industry that would far outnumber those you listed. And even within those you listed, those working on the mission critical parts are a very tiny fraction. Statistically, that is almost no-one.

E.g. there are 100s of millions of lines of code in a car, but the vast majority of that concerns non-critical parts like the dashboard; the primary Engine Control Unit has like ~10K LoC, and the number of people that work on it are proportionally smaller.

And if you think that is very well-designed code, here's something to help you sleep better: https://www.reddit.com/r/coding/comments/384mjp/nasa_softwar...