I think AFMA should be standard in ANY camera, but I do understand why it is not. I also seriously doubt it costs zero to add. As a professional software tester I believe that adding this feature to ANY camera model would include testing of that feature. (at least some regression testing)
Although lots of testing can be automated, and one can limit oneself to spot testing (not testing every camera body), it will still cost human effort, and as a consequence, money.
So, unless you actually work at Canon, and was present at the meeting where the QA responsible took the decision to take the risk of never testing AFMA in a new camera body (and can prove that to us), I would not claim that I know how much it costs to add.
It could still be cheap, when you spread it out on the volumes for these cameras, but we do not know that, and in this end of the camera spectrum, cutting manufacturing costs is good practise.