I agree that the primary reason for it is the newness of it all. However I disagree on the disposition point. The question for me is more around the extent of the difference, how significant it is, and how much it comes into play. That there is a difference at all shouldn't be surprising given that Ireland has a very different history and national story in comparison to the vast majority of other 'Western' nations.
& Disposition is a better term than predisposition. ;)
They haven't made the same sort of inroads here because the cultural/social changes that this country has undergone in relatively recent times happened in those other countries a generation or two prior.
Who's Rowan Croft btw?