Having recently done 2300 miles in europe and in comparison it's quite an eye opener how discourteous drivers are in this country.
Driving down through France was a total breeze. OK. They have very little traffic on their motorways so probably a bad example. Italy generally had heavy traffic with a lot of lorries on the roads I was on. Even still, people were, on the whole, in the correct lane. Most followed too close for my liking but that's another issue. They pulled over when you came up behind them.
Austria and Switzerland were fine too.
I found Belgium pretty much like here, and Germany was interesting, to say the least.
The main factor I can dig from this is that when the speed limit is 130 KPH (just over 80 MPH) and enforcement is not as anal as over here, a cruising speed that satisfies everyone is within the law and the range of speeds is much less. There are slow vehicles doing 55-60 and everyone else cruises at around 80-85.
Here we have drivers who want to cruise at 90+, drivers who see 80 as a bit naughtly but unlikely to get them into trouble, those who stick religiously to the speed limit through "speed kills" brainwashing and won't break the limit even if they end up driving parallel to the vehicle they are trying to overtake and caravans, lorries, etc. that cruise around the 55-60 mark. I even often come across car drivers who cruise slower than lorries, forcing them to overtake

It all went horribly wrong in germany again for the same reason. One lane is taken up by lorries and moves at 55. The other lane is a mixture of vehicles who want to travel anywhere from 60 MPH to <insert maximum speed of S class merc>. One nice thing was that lorries are banned from the overtaking lane on 2 lane dual carriageways / motorways, ending the practice of "snail racing". When will they do that here?
Belgium has a speed limit of 120 KPH and I think this explains the fact that it was much like home.
Anyway, that's my theory. About time we upped the limit to 80 perhaps - not that the "speed kills" lobby would entertain that for a minute.
Kevin