[user5994461]

The majority of critical software is C, sometimes it's C++ or Ada instead.

C++ actually proved difficult to adopt over C. The language is too difficult and the tooling is too poor. It's too hard to run a static analysis or prove 100% code coverage.

[jb1991]

I'm not sure what your evidence is for this, but I find C++ to be used far more widely than C in nearly all the companies I interact with that do critical low level work. And there is indeed plenty of information in the industry about flight control software in particular in C++. It's also very popular for embedded work, because C++ allows you to offload quite a bit of work to compile time that can only be done in C at runtime. And I've attended talks for security systems in C++ specifically because of control over exceptions and how to track unexpected events, which is something security professionals are very interested in.

With regards to tooling, the windows visual studio experience for C++ is widely counted as one of the best development setups in the industry for any language. I know lots of people working in other languages that envy what C++ developers get.