I hope someone can come up with some constructive ideas here because I would like to be a voice should I see something of the sort. This is heartbreaking.

It's a tough call though, if someone can be so nasty to their own kid, they can certainly be worse to a stranger trying to intervene. So for the sake of their own kids, I'm not too surprised those women didn't do anything or say anything. I'm just going to bet that the situation was very tough for them in the moment even if they didn't outwardly react to it - like maybe they were paralyzed in a way by it because they were caught off guard.