Originally posted by reh321 Shouldn't be strange at all. F-mount is like K-mount. Only recent lenses have in-lens focus motor. To provide complete service, the adapter has to provide a focus motor, which is much more difficult that providing the contacts required by the EF-mount.
F-mount seems to be a generation ahead on development over K-mount.. at least in terms of introducing in-lens autofocus motors. Perhaps the stripping by Hoya and purchase by Ricoh is the reason. I think when Ricoh introduced HD revisions, is when we should have seen more in-lens motors. But they just didn't have time or the budget to complete such a monumental task.
Not sure any G series lenses are without a motor (AF-S primarily --- ultrasonic motor)
I think most of the older D series lenses, from the early to mid 90s, are closer to a lot of the K mount lenses still on the market (screwdriven).
So the adapter doesn't need to provide a focus motor for a very large amount of Nikon lenses on the market today. As a matter of fact, here is a handy dandy listing of all the available in-focus motor driven Nikon lenses:
List of Nikon F-mount lenses with integrated autofocus motor - Wikipedia
I really just think it boils down to Canon having a stranglehold on the market with number of users (and thus potential buyers) and a large selection of desirable lenses. So you have Canon users wanting to adapt their lenses to use on mirrorless bodies (typically Sony) and maybe a few mirrorless users wanting to try out Canon lenses..
Edit: Did you mean electronically controlled aperture instead and not in-lens focus motor like you said? That might make more sense..