That’s assuming no disease, mental illness, unforeseen events, injuries, forced poverty, unexpected deaths, etc. A great deal of family dynamics is outside of a person’s full control.

Did the drunk wife-beaters intend to be that way?

I think you're too idealistic (or of right wing ideology). The culture aka parents inlaws and random aubties and uncles pressurize Indian couples to have 1 kid then 2nd kid then 3rd kid

But neither of them come to help these days with childcare. Just for the photos and for lolz

Very few couples have kids of their own violitin

Not to mention some religious sects/cultures who look down upon contraceptives due to religious beliefs

So yeah, loads of parents become parents by accident and not by their own choice. (Not saying everyone is like this but a large number is like this)