The area of Rust code that is unsafe is much, much smaller than the amount in equivalent C code, making it much more tractable to audit. I won't pretend that it's perfect, but it's not remotely comparable to C.
fn do_something() {
unsafe { ... }
}
// Somewhere in the program
do_something();
Doesn't matter where "do_something" is used and how much. The only possibly problematic part of this code is the unsafe block. You only audit it.