Yes they are breaking the rules of the road and being ignorant, but generally we who are grumping about them aren't totally innocent either!
I was with a guy in a van last week and he was grumping about just such people whilst we were on the motorway, I had to point out to him that we were actually doing 80 miles an hour so were breaking rules too!
As for it being different in Europe, what tosh! I work in Belgium and Germany on a regular basis and their standards are far worse than ours, they do have less triple lane carriageway though so it doesn't confuse people as much so they tend to move over! The standards of driving especially around the larger cities in Europe are dreadful! The amount of accidents I see every morning is far far greater than here in the UK.