@BrodieOnLinux Source?

They did have to wait years for Mach's licensing issue to be resolved and wrote other parts of GNU while they waited.

Nobody could use any Berkley Software Distribution software for many years as they had handled licensing poorly from the start, plus used things like the 4-clause BSD (as soon as you combine more than 2 pieces of software into a system under that license, the requirements turns into a bad joke).

While GNU re-used existing software if it existed, it avoided software under unclear licensing terms, as there was a real risk of a business turning around and saying "that software must be proprietary" and GNU would have no choice but to drop everything that was developed.