Historical accident.<p>I used to do systems programming back when the only OS written in C was UNIX.<p>C wasn&#x27;t the first systems programming language.<p>Burroughs B5500 was written in Algol 68 with zero lines of Assembly. Just one example from many others in the pioneering days of computing.<p>There are other approaches to writing OSes.<p>If UNIX community ever wants to divorce from C there is a way, but there needs to exist a will as well.