Its not so much this particular instance... but if this kid is taught that its OK to act like this... one day she is going to do it to the wrong person and someone is going to find her in a ditch.
You can’t just talk to anyone however you want to. Oh you might get away with it a few times....
My kids know that some people are evil, real evil, and they understand that. Sensible people don’t just scream at an evil person. This mother is taking advantage of the decency of people who make her feel insecure, and as you say it could cost the little girl everything. The woman is a terrible mother, and as a result it doesn’t look like the girl has much chance in her life.