I am willing to concede that "Rust" is safer than "C".
However, in "unsafe Rust" it is super easy to violate a Rust API precondition that the compiler takes advantage of. Even the Rust intelligentsia have pointed out that writing correct "unsafe Rust" is significantly harder than writing correct C.
To add on, unsafe Rust's main strength is the tools and the culture of encapsulating it well. It's probably the case that "well designed code that uses unsafe" is much safer overall, as you would expect for a memory-safe language. But it doesn't just come about from using unsafe.
