> Nope. X protocol knows nothing about subpixel order. Wayland does.
Both X and Wayland request information from display. If that information is available there they can read it. Both. Or do you thing that Wayland is reading the mind of display creators, while Xorg can't do that? ;-)
> Xranrd in this case is a cop-out because it's not universally available.
Run `xrandr --verbose` and see "Subpixel" there. Now think, if xrandr gets information from X-server then X-server knows about subpixels, and X11 protocol is able to transfer that, right? Just read the protocol if you still don't believe me.
> Wayland exposes the surface orientation to applications (surprise!)
Indeed, it's a surprise, could you point me to that part of the Wayland protocol?