Blog (and DCI) muse mount complexity limit the EOS-M and Fuji-X mounts.

A article noted by Northlight and subsequently DCI reports the following information. Machine translated.

However, in Sony or Micro Four Thirds cameras, lens information (lens identity) is properly read on the body side to make optimum correction even if it is a lens made by another company made by Sigma.  It is because Sony has conveyed mounting information (a method of exchanging detailed information between the lens and the body) to the Sigma side. Because it tells information of E mount if you make a deal with Sony ─ ─ It seems to be the black box at the very heart of the matter, and you have to explore with 'your own power' later.  Meanwhile, in the micro Four Thirds you can get all of the mount information if you put it in that forum. 

But neither Canon nor Nikon nor any other manufacturers will issue mount information at all. If you are trying to make a compatible lens, you have to fumble and find mount information. MF lenses would be relatively easy, but it would become extremely difficult to become the latest compatible lens compatible with AF.  Since Sigma and Tamron have been making compatible lenses since long ago, since the mount information has been simple enough to respond precisely from the MF lens era, even if it becomes a complex strange mount information as it is now, we can manage it I'm coping with the rewriting of the firmware by mistake. 

It is said that it is very difficult to make compatible lenses from this time by searching for mount information of new cameras in this era even with a lot of effort, human power and technical power.  It seems to be the reason that this Sigma 16 mm F 1.4 lens has no compatible lenses of Canon EOS M series and Fujifilm X series, and there are only two mounts of Sony E mount and Micro Four Thirds (in the future, possible Maybe it will be). 

To be honest, this is a bunch of hogwash.  The EF and EF-M mount protocols are exactly the same.  The EF to EF-M adapter is downright stupid with no adaptive electronics.  Tamron has released an AF lens for the EF-M years ago.  It's the same size as an E mount and Sigma already knows how to adapt an AF lens for the EF mount.

A while back I sent an email to Sigma USA and asked them why they don't make EF-M lenses and the simple response was "not enough demand".

I guess that's saying there simply isn't enough demand for primes with the current user base of EOS-M cameras.  I can appreciate that, the zooms are darn good, and Samyang makes a slew of cheap and great manual focus primes as well.

So if you want AF Sigma primes on the EOS-M, let your voice be heard to Sigma ;)