Dealing with parents who don’t discipline their kids

Looking for some advice here. A mom friend has a very hands-off approach with her toddler and doesn’t really discipline her at all. We ran into a situation where her child was trying to take a toy my child was playing with, and she got super upset when she couldn’t get it. She started screaming and hit my child, then went into tantrum-mode. My friend saw all of this and didn’t do anything, just sort of gently suggested they share. I was in such an awkward position. My child is older and wasn’t hurt so I just let it play out but I was really angry and felt she should have intervened since her kid was acting out. Next time I will do something, but what’s the proper thing to do in this scenario? It felt awful for my child to look at me like, “Hello...don’t you see what’s happening here? Do something about her!” via /r/Parenting https://ift.tt/2VDDa5w