> Users can inspect and modify the entire system, no?

That should make the Smalltalk family popular with free software proponents. That makes me curious why that is not the case in history. The efforts of FSF on Smalltalk pale in comparison with those on C, Lisp and other languages.

C was only open until AT&T was allowed to charge for UNIX, and it became an international standard in 1989.

It was thanks to GCC that most folks actually got a free C compiler after those events, coupled with Sun starting the trend among UNIX vendors that developer tools would be extra license, no longer available on a regular UNIX installation.