By default Rust statically links the standard library into every program. For binaries it also statically links to jemalloc by default to use as the allocator. This is a large constant factory that makes trivial programs significantly larger than C, but like all constant factors it becomes insignificant when n is larger.

Binary size is not a major concern for most programs, even those written in a systems language. If it is a concern for your use case, you can use dynamic linking and the system allocator to get the size down to the same scale as C.