That's because children are seen as innocent. We can blame someone in poverty of "making bad choices"... What choice is there for a newborn to make bad choices?
Yet, we have little issue,society speaking, condemning a baby and their family to a life of poverty to continue that cycle.
Or should we say that the newborn/baby deserves lack of medical care, substandard food or hunger,substandard housing, less/lacking education? If you believe they deserve that, can you explain what actions a baby can do differently?
Hard work of the parents doesn't really factor into it. It's the social standing of the parents. A single mom who works 2 jobs works harder than most of us on this board. Yet, our kids are going to have it much, much, much easier than hers would.
"Why is it not acceptable for someone that had better parents to do better?"
If your whole schtick is about "meritocracy", then having people start out better by default defeats that entire thing.
Just about every study done on the subject shows that the family you're born into has a HUGE effect on how successful you'll be in life.