You can have data races in "safe" Go. If you race a trivial object [such as an integer] it's just radioactive and so long as you didn't need it to have any particular value (e.g. you were just going to write it to a log anyway, or you just discard it) you're fine. However if you race a non-trivial object then that's immediately Undefined Behaviour.

Of course Go programmers will say "Just don't do that" but that's exactly what C programmers told us about bounds misses, use after free and so on...

(Memory) safe languages are allowed to guarantee memory safety at any stage, including at runtime using GC and bound checks. That makes every GC language memory safe to a reasonable extend. The novelty in Rust is that it does the same at compile time, mostly automatically.