I have some direct experience. After mom divorced dad in 1970, I got to be a latch-key child. After school, I waited for dad to get home. Mom remarried a single dad with three older boys and gave everything to them. I was withdrawn and depressed but not aggressive. My guts were in knots for 25 years. I don't have one tat or piercing, have done ok education and career-wise and I have a very good foreign-born wife of ten years.
I was reading a book by Samuel Pufendorf which had a chapter on how men naturally have a sense of honor and self-worth and should treat each other respectfully.
It got me to thinking, I couldn't have expressed it back then, but small children have a sense of honor too which they cannot assert. Small children dumped in day care, nurseries, palmed off on others, will feel dishonored, disrespected, by their own parents, to the point of excruciating, but will be unable to react as an adult would by challenging the dishonor and insisting the other party make it right.
Perhaps as an adult, the child will figure it out and put the right words to the feelings, or not, but either way, we will likely find these same kids don't want to take care of mom and dad when they get old. Mom and/or dad, may find themselves in nursing homes to a larger degree, and not the nice ones either.
Maybe the children, grown, will show up to say coochie coo from time to time. Or not, if it isn't convenient. Perhaps we will be reading some years hence, how "Nursing homes still breed aggression' (New study points out behavior problems r/t nursing homes)
What goes around comes around.
Interesting thoughts. Probably what the kids are interpreting being left in daycare is that their parents don't want them and if your own parents don't want you, who does? Every kid knows that parents are supposed to love and want their own children, at least, even if they can't stand anyone else's.