$ cat helloworld.cpp 
    #include <iostream>

    int main()  {
    std::cout << "Hello world" << std::endl;
    }

    $ g++ -std=c++14 -Os -static helloworld.cpp 
    $ size a.out 
    text    data     bss     dec     hex filename
    1294232   29692   92936 1416860  159e9c a.out

    $ cat helloworld.c 
    #include <stdio.h>

    int main()  {
    puts ("Hello world");
    }
    $ gcc -std=c99 -Os -static helloworld.c 
    $ size a.out 
    text    data     bss     dec     hex filename
    725706    7572    9080  742358   b53d6 a.out

Yes, a simple "Hello World" winds up statically linking a fairly sizeable standard library, in particular anything dealing with strings has to involve a certain amount of UTF-8 manipulation and the formatting and I/O have a lot of features and thus likely fairly large code size. But for the most part that's just fixed overhead, and you can opt out of using the standard library if you want and produce smaller executables.

If you want tiny binaries using dynamic linking then you can use "rustc -C prefer-dynamic".