Wikipedia allows "fair use" as justification for including non-freely licensed works (see https://en.wikipedia.org/wiki/File:Blue_Poles_(Jackson_Pollock_paintin

Wikipedia allows "fair use" as justification for including non-freely licensed works (see https://en.wikipedia.org/wiki/File:Blue_Poles_(Jackson_Pollock_painting).jpg#Fair_use_rationale_Blue_Poles https://en.wikipedia.org/wiki/File:Blue_Poles_(Jackson_Pollo... for Blue Poles specifically) while Wikimedia Commons does not.