On Sat, 08 Oct 2011 16:46:41 +0100, "Dave Plowman (News)"
wrote:

A vehicle with power steering is far heavier to steer when the assistance
fails than the same vehicle fitted without power steering.

Exactly so. Different (and heavier) steering geometry in a lot of PS
designs, as well as the obvious rack or worm gearing differences -
although some had the same geometries from non-PS to PS versions.