{out of usual lurk mode} These statements demonstrate that the family in question and the OP are worlds apart, even in the US.
Most kids put in this situation are not "decisions to have a child" in the first place. Accidents happen, prostitution for drugs happens, irresponsible use of contraception happens.
With that premise in mind, having funds to raise the child is not even a consideration. Adoption is not usually considered because of loss of medicaid when parental rights are signed over. Having the estimated tens of thousands of dollars it takes to raise a child to the age of 18 does not ever enter into the equation. That money comes from John and Jane Taxpayer.
They can breed 'em. Almost like rabbits, I sometimes think. That is their constitutional and inalienable right, and none of us can even Try to take that away from "them". You and I feed 'em and care for them, through WIC, ADC, Medicaid, etc etc.
Grandma and Grandpa may have aged into middle class and brought granddaughter into it by default of Mother's drug habit. I would be skeptical that Mother is a member of the middle class, and would not have acquired the sense of responsibility reflected in your post, above. Totally different worlds.
FWIW, I've taken care of these folks from the obstetric (delivered them) and gynecologic (contraception and sterilization) perspectives, and now from the psychiatric (read ADHD, coke kids, drug abuse in kids and adults, kids on foster care, foster parents thinking they have guardianship when they do not, narcissistic senses of entitlement, and people who otherwise want what they want when they want it.) Totally different world compared to the white collar community in which I was raised.
Linda H., M.D.