It appears that the version info functions in the Win32 API that I know and love have changed their behavior. GetVersionEx now return what the program's manifest is set for, not the actual version.
The new function IsWindows10OrGreater
seems pointless since it is only available on windows 10 or greater, so if the program includes it and successfully links it will always return TRUE.
But, in an installer or similar program, how does it determine whether the current environment really is Windows 10 or greater? It needs this to know what to download or which options to set up for other programs.