I believe the way the OSM community goes about "enforcing" the license is lacking on many fronts, which I suspect is a sentiment shared by many (but not most) mappers. I have a proposal for addressing the problem a part of which is mass identification of the users of the tiles and the offenders, but also introduction of a (hopefully) community-acceptable way to enFORCE the license.
As a first step I wanted to get at least rough numbers about the scale of the offenses. I will present the proposal either on the legal talk list or write a blog post.
I've sent https://news.ycombinator.com/user?id=matkoniecz, who is on the OSMF board with me and likes to work on attribution cases, a link to this thread. Feel free to post the offenders you've identified here for discussion.
In case that you would go through them and manage to identify problematic cases: can you share list?
Either here, contact me somehow or even add cases to https://wiki.openstreetmap.org/wiki/Lacking_proper_attributi... listing?