Then how do you account for billions of all-metal floor and table lamps that are sold and used with a simple two-wire cord and molded plug? A floor or table lamp is far more accessible to occupants than a ceiling mounted cord and plug supplied track luminaire, and almost always require the end-user to grab the luminaire to find the key or switch to turn it on and off. These factory assembled luminaires are rarely ever grounded.
My point is that the factory assembled cord and plug live-end feed, attached to a track of the same manufacturer, is a manufactured luminaire, not a luminaire that is wired in the field by the installer; and therefor the Article 250 grounding that I would have to do if I, as the installing electrician, assembled it's wiring in the field, does not apply.
And, no, inserting the live-end field into the track rail does not constitute the "wiring" of the luminaire, in my opinion.