Well, there has been a long campaign against manual memory management - well before Rust was a thing. And along with that, a push for less use of raw pointers, less index loops etc. - all measures which, when adopted, reduce memory safety hazards significantly. Following the Core Guideliness also helps, as does using span's. Compiler warnings has improved, as has static analysis, also in a long process preceding Rust.

Of course, this is not completely guaranteed safety - but safety has certainly mattered.