Why do tectonic plates have a tendency to drift closer to the equator?
I'm not a tectonicist or a science historian, but as far as I know the ‘pole flight force’ or Polfluchtkraft was introduced by Wegener in his theory of continental drift. Essentially it's just the application of centrifugal force to continents (or, if we are now considering it within the plate tectonic paradigm, to plates). As stated in the Wikipedia article you link to, this force is far too weak to account for plate motions, and this very fact was one of the reasons for the scientific community's rejection of continental drift. Modern tectonics doesn't seem to consider it even as a measurable contributing factor. The only modern references I've found to it have been in historical contexts, such as in Krause (2007). The subtitle of this paper, ‘Vergessene Begriffe der Geologiegeschichte’, translates to ‘forgotten concepts of geological history’, and as far as I can tell this is an accurate summary of Polflucht's current status.


Krause, R.A., 2007. Die Polfluchtkraft: Der LELY-Versuch
– Vergessene Begriffe der Geologiegeschichte. Polarforschung 76 (3), 133–140. DOI: 10013/epic.29962