My bad. I read the docs, but mistakenly believed platform support meant OS. I figured since Windows maketh then Windows should taketh. I've spent the day studying the _datetimemodule.c code and now realize my error.

Question -- it seems to me an unnecessary limitation.  If someone were willing to submit a platform neutral version of localtime/gmtime that worked identically on all platforms, would this be met with eagerness? Or more of a shoulder shrug?

It's a fair amount of effort, and I'm willing to commit to it, but if the issue only matters to me, I can work around it.