Thi question focuses on airbus since the [A320](http://www.airliners.net/photo/Spirit-Airlines/Airbus-A319-132/2628258/&sid=cd6780594f3ce92a53ca9e2c3cd6769d), but is not restrited to thoses aircrafts as the situation seems to be the same for [other aircraft](http://www.airliners.net/photo/Delta-Air-Lines/Boeing-747-451/2703428/&sid=bdfb3c23256e47a16501c826e140138e).

In front of the left seat, the navigation display is displayed at the right of the the primary fligt display, and it is the inverse of the right seat.

Is there a technical reason to do so? An historical one?