There was a point in time where the US government was considering mandating POSIX compatibility in everything. It's why Windows NT shipped with a comically bare

There was a point in time where the US government was considering mandating POSIX compatibility in everything. It's why Windows NT shipped with a comically barebones POSIX subsystem and why A/UX (an Apple port of Unix to the Macintosh, years before they bought NeXT) existed.