I would not necessarily expect it but I appreciate it in a "systems" language where "systems" is defined as compatible with the existing traditional systems software on a machine. For example, it's nice if the stdbuf(1) command works on Rust binaries on glibc systems, and it's nice if a Rust binary calling a C library that writes with printf (or vice versa) don't maintain two separate output buffers.
To me, Go is the systems programming language for a world untethered by existing platform compatibility (and so, for instance, writing Go libraries to be called from C is awkward, calling C libraries from Go incurs overhead, Go has its own concurrency model, etc.) and Rust is the systems programming language for use cases where you'd otherwise want to use C (really "the platform's native systems language," but that's C on all the major platforms) but you want a better language. I appreciate that they both exist and target these different use cases.
