There's even unsafe usage in the standard library and it's used a lot in embedded libraries.
Sorry but horrible comparison ;)
If you need to rely on unsafe in a memory-safe language for performance reasons, then there is a issue with the language compiler at that point, that needs to be fixed. Simple as that.
The whole memory-safety is the bread and butter of the language, the moment you start to bypass it for faster memory operations, you can start doing the same in any other language. I mean, your literally bypassing the main selling point of the language. \_00_/
It actually means "Rust needs to interface with many other systems that are not as stringent as it". Your interpretation has nothing to do with what's actually going on and I am surprised you misinterpreted the situation as hugely as you did.
...And even if everything was written in Rust, `unsafe` would still be needed because the lower you get [to the kernel] you get more and more non-determinism at places.
This "all or nothing" attitude is boring and tiring. We all wish things were super simple, black and white, and all-or-nothing. They are not.
Once you can internalize that you could unlock the power of encapsulation.