OMG! I get this!
I ran into this in college with my roommate's parents. When they found out I grew up without my father in the picture, they immediately assumed that I grew up in some kind of abusive, loveless, uncared for, abject poverty situation.
They assumed that I was not well loved by my entire extended, close-knit, family, and prided by the people in my community!
I still see this attitude when white and non-Black PoC seem surprised that the Black community reveres, cares for, and respects our elders, and that I respect and care for my own. I've seen this in their assumption that any Black people they encounter got to where they were all by themselves, with no support from their greater community.
I guess, if they don't see us doing it on a TV screen, or in the news, then its not something that's actually real, or even true, to them, because this is echoed in "diversity "media, where we see token Black characters, without families, or communities, interacting, and supporting one another. Pop culture and mainstream media is another thing that only reinforces the belief that we don't have bonds with each other, or care about each other's lives.