I'd never heard of Soda Bread with Raisins and Caraway before and for what it's worth a bit of Googling reveals that it's not an Irish thing at all but an American style Soda Bread.

So why the 'Irish' descriptor? At a guess I'd reckon that it is a recipe which the wealthier (you don't get butter, eggs or dried fruit in Irish soda bread) descendants of poor Irish settlers adapted from the plain stuff their ancestors arrived with?

Incidentally, I recall reading a great little book about the multitude of breads that different European settlers brought with them to the New World, the author reckoned that bakers bringing their trade with them would keep a precious wadge of yeasted dough safely behind one ear, to keep it warm and moist, ready to begin baking with as once they reached land.