Forgive me for not remembering the textual source of this comment but I
distinctly remember reading a magazine article that concluded that there is
essentially no statistical safety benefit in having dual controls installed
in an airplane.  Yes, it does permit dual instruction and a left-seated
pilot to land in an emergency but there are other considerations that offset
these advantages.

There are the obvious factors including more equipment, complexity, build
time, maintenance time and cost.  Beyond these, the article concluded, after
analysis of relevant accident data wherein the dual controls were a factor
(both plus and minus), that dual controls caused as many accidents and, yes,
fatal crashes as they prevented.  The primary reason for this was that
passengers, often who were non-pilots, would interfere with the controls by
standing on the toe brakes or inadvertently "pushing" the yoke (stick) left
or right and/or up or down.  Additionally, objects carried in the plane that
were loose in the cockpit would jam the controls on the right side out of
reach of the pilot.

Does anyone else remember reading that article?

I religiously practice "Kiss"; I don't have dual controls and have never
regretted it.  Further, not having dual controls prevents me from giving
dual instruction which I am not qualified to do anyway (thus, I, my airplane
and passengers are all safer).     Greg Nelson