I am an outsider who has not personally written anything in Ada/SPARK or Rust. But I have worked at companies that transitioned (or started to transition) from

I am an outsider who has not personally written anything in Ada/SPARK or Rust. But I have worked at companies that transitioned (or started to transition) from C/C++ to Ada/SPARK and from C/C++ to Rust. I suspect that there are a few additional factors besides politics that prevented some C developers from taking Ada/SPARK as seriously as they seem to be taking Rust. 1) Ada and SPARK still retain a whiff of academic/military design-by-committee which prejudices a certain kind of developer. Whereas the Rust team has been open-source from the start. 2) The military projects I am familiar with started switching to Ada (and later SPARK) due to the US DoD mandate in the 90s. Of the people I know who use it, many of them started using it because their job required it. (Though to be honest many of them now love it!) Whereas Rust adoption seems to be largely driven by a hearts-and-minds initiative to convince regular developers that memory safety is a problem in C, and that they should choose Rust to solve that problem. 3) Syntax. Some C developers don't seem to consider a language a Serious Programming Language unless it uses curly braces. (Just ask a C/C++ developer about Lisp's parentheses or Python's whitespace.) Whereas the Rust team decided to hew close to the conventions used in C wherever appropriate.