Things that are written in C these days are usually written in C for performance reasons. FFMPEG would not have even close to the performance it has if it was written in a memory safe language instead of C and assembly. I doubt that a magical compiler (and/or language) will appear in my lifetime that can compile high level code into performant machine code, especially when it comes to memory management. (note that C also has advantages other then performance)

JS doesn't even have a proper specification, let alone a bug-free interpreter/compiler.

EDIT: AFAIK verifying memory access is part of a formal verification, where memory is also modeled mathematically.