You turned on a feature which helps diagnose this type of mistake at runtime, and it helped you by diagnosing the mistake at runtime. What does that prove?
What I'm talking about is that Rust's Option is very cheap in all the cases where it can be very cheap, which makes this whole design feature more affordable. C++ eventually grew std::optional which is not powerful enough for this work and yet is also bigger and slower. They could have done better, but safety wasn't a priority.
It proves that there is a way to diagnose this type of mistake, that is what matters.
Unlike C, which the only way to be safe is not to touch it at all.
As for performance, ISO doesn't implement compilers, there are many ways to improve performance while keeping the semantics in line with the standard.
If the compiler vendors decide to focus elsewhere is another matter, a bit like there are languages as complex as Rust and compile faster, because that has been a concern, whereas rustc developers have their concerns elsewhere.
https://godbolt.org/z/vYcMhE9h7