The institutional cruelty meted out to these women and kids didn't happen in any other European catholic country and it didn't happen on such a scale in any poor country.
I think that it is related to Famine trauma. Israelis demonstrate similar levels of cruelty to Palestinians and it is only 80 years since the Holocaust.
After the Famine sexuality became strictly policed and average age at marriage increased significantly
In an agricultural society the subdivision of land ended.
There was SFA other wealth
Unexpected children were a threat.
The Famine was a watershed - but for Catholicism. Because of the humanitarian work of the Quakers for example, some communities were too appreciative (to the 'detriment' of the Catholic 'faith') so Archbishop Paul Cullen brought about a new 'devotional revolution' which spread like a 'frenzy' apparently. Dingle and Tuam get particular mention for the dramatic nature of the sermons. This drove a renewed devotion which led to the abuse of 'Catholic Church' power - against 'evil'. This evil was personified in the mothers and babies of the homes, born out of wedlock, so the nuns, in their belief, were simply "ridding the land of evil" hence the cruelty. The nuns, remember, were also indoctrinated - to think that they were doing the right thing, God's work.
I don't think that 'unexpected children' were a threat to anyone except the righteousness and 'purity' of the Catholic Church.
Sin é! I'm away to say a decade of the Rosary!