Comment by klibertp

I'm not sure. You'd have to define "level of rigor". TypeScript has a vastly more expressive type system than C, for example, so given their respective prevalence in their domains, you could easily say that coding apps nowadays is actually more rigorous. There's Rust, but somehow people write lots of apps in it. And so on.

I don't think systems programming is inherently harder than writing apps. You deal with different sets of problems (users stubbornly misusing your UI vs. hardware vendors notoriously lying in the manuals; hundreds of dependencies vs. endemic NIH syndrome; etc.), but coding is, for the most part, the same thing everywhere. IME, the "level of rigor" (as in "kinds and pervasiveness of actions taken to ensure correctness") depends much more on actual people or organizations than on the domain.