Originally Posted by
AerocatS2A
The autopilot is a machine that will apply the required input to achieve the desired result. It doesn’t have expectations or past experience to fool it into doing the wrong thing. It doesn’t care if the “stick forces” change as it applies more elevator, it just does what needs to be done.
This is only true for a system that is basically stable and where a linear input produces a proportional linear output. Controllers for systems which have less or no inherent stability are highly complex and their design needs to incorporate more factors and functions and limitations than a "simple" proportional controller. It took years for instance to develop the stability controller of a Harrier jump-jet in the hover state. In an aircraft, a crossfeed of the other axes and/or configurations may also be required (e.g up-stick when the plane rolls into a turn). An autopilot that needs less up-stick in a standard turn than in a tight one might not be easy to implement.