Of course, most languages *could* do so, but by adding in a C compiler to them all, you are adding in extra complexity for a niche use case, and when you start doing things like that, you should stop and ask yourself "why"? You are both constraining the language you are altering and forcing it to have concerns about "C" type things that the language designers may have very consciously designed out, like pointer arithmetic and memory management. Plus, you are essentially forking the C compiler each time, and having lots of separately maintained forks of the same thing NEVER ends well.
As a rule of thumb, you should only add to something that which you need; it reduces the maintenance cost, and makes the result measurable and testable.
If you have discrete interfaces for the functionality you want to export from one language to another, then you can worry about the maintenance of that code in its native language (in this case C) and only have to concern yourself with consuming the interface in the host language. Traditionally, this was through entry points in DLLs, which would have a clearly defined interface. If your target language didn't support the required types (for example, if the DLL advertises an entry point with a signature that requires an unsigned short, but your language only has 32 bit signed integers), then you would build a shim to handle that.
I would expect that these OS system calls work in much the same way, except you just specify the namespace they live in, and the language now knows about them without you having to declare the entry points explicitly, and handles all the nastiness like memory management, and building structs with various char*s or whatever in them, where it is needed.
The key here is separation of concerns - In this case, you don't really want to be having to build various libraries every time you use them, that is the concern of the person who supplied them in the first place. You only want to be concerned with your code that consumes them, so why would you need that C compiler to build them anyway?