Most of the surviving narrow gauge lines in Europe have become tourist lines, so no need to haul freight anymore, but as late as the mid 1990's I saw standard gauge cars being hauled to and from a clay mine on the Oschatz - Mugeln 750 mm gauge line in the former East Germany. The motive power was an 0-4-0+0-4-0 articulated Meyer Lok.
The Harz meter gauge line and some of the 750 mm gauge lines have kept a few roll wagons to use to haul standard gauge cars for photo freights. The problem is in obtaining the proper standard gauge wagons. Most of the period correct ones have been scrapped.
Michael Allen