One problem is older drivers who passed their test in the 70s or earlier, and don't realise that driving conditions (and the Highway Code) have changed condiderably since then. An elderly friend of mine was pulled in a few years ago and advised by the police that he shouldn't negotiate a roundabout like that nowadays as the recommended way was completely different, and I don't know how many roundabouts there are in Ireland but I've never seen a Dub negotiate them properly, even the long-time UK residents.