alt Hacker News> C (where the safe subset is effectively empty),
Well, Fil-C and also Cheri show that C is a language that can be implemented with perfect memory safety for 99.9% of the language. This is not true for every language but is also not an accident in C. But also with the typical implementations of C such as clang and gcc you can essentially get spatial memory easily by using safe abstractions.
Very explicitly making a silly point; a rock is 100% memory safe.
The serious point: I care about whether the program I write aborts regularly, whether due to a Rust panic or a capability violation.