> Imagine they had done this for certain other things. Like errno, with all the brokenness of the locale API. They did. See for example time functions like loc

> Imagine they had done this for certain other things. Like errno, with all the brokenness of the locale API. They did. See for example time functions like localtime (and localtime_r) and tzset. It is admittedly locale adjacent, since it depends on the locale. But the time zone is also global state, so it is impossible to get the time in a different timezone with standard apis in multi-threaded portable (for posix) c code.