Peering disputes in Europe center around different carriers generally. But the basic dispute is the same, carrier A doesn't want to peer with carrier B, probably for business reasons, so they try to setup their peering rules so that carrier B doesn't qualify, or they won't upgrade connections.

I know I've seen some carrier names that come up in those disputes a lot, often the incumbent telco for a particular country. But you've got a lot of countries there and most of them had their own nationalized phone company, and only one or two end up having public spats over peering. There's similar stuff in some countries in Asia, where some of the incumbent telcos refuse to peer locally. (and of course, China has the GFW)