Yeah this is exactly the kind of thing I mean. I worked at the company that makes CMake and I'd go to coworkers with questions like that...I forget exactly what I asked but it was something involving RVO and copy elision of a lambda/ anonymous function, and they had to ask around until we found a greybeard who knew the correct application of && and some other stuff. This wasn't even some heavy deep stuff, it was like a pubsub callback in ROS.

I had some really mission critical camera driver stuff I was working on and just never felt secure that there was a massive bug lurking, despite code review, Valgrind and testing. But on that same project, I had enough confidence to write a small daemon in Rust, with like...maybe 60h total experience in the language. Huge peace of mind knowing the code does what I expect it to do.