We have decades of coredumps and exploits to convince us that nobody can. How many well-known apps can you name that have never blown up randomly? I can't think of a single one. How much more failure until it's reasonable to think that C requires an inhuman level of perfection and almost any alternative would be an improvement?
I hear good things about seL4 but that wasn't written so much as translated from Haskell during a formal process that makes Rust look like finger painting.