From some time I've observed very strange thing:
Most of uploaded on commons copyvios is made by users who has spanish-like nicks, write in looking in this manner language, etc.
Because I see very large time coincidence with closing upload on es.wiki, I have (I hope) very good method of solving that:
I'm going to ban every user who will look like from es.wiki to me, without any warning after first upload.
Maybe than complains of such users will force them to open upload :)
AJF/WarX