analog

Totally jusitifed, random people (regardless of sex) have no right to touch your kid in any way.

But that's not what happened- not even close. That's a totally different scenario and not in the least comparable to what really happened. You're talking about imminent threat of a kid falling out, with parents outside of reach. That's one thing entirely- this was a situation where both parents were already present and working on the issue. Here's the important bit: there was no imminent threat of danger. The kid just caught himself on the carriage.

Short of imminent threat of serious physical harm, you have no right to touch someone else's child.

I don't care if you OR the other woman are pediatricians of 30 years and mothers of 20 children, you have no right unless there is a serious threat of immediate physical harm- which there was not.

EDIT: I don't understand how so many people in here think slapping a hand is bad in comparison to a stranger attempting to touch your child. Someone went so far as to call it assault. Are you serious? They reached forward with the intention of touching a child without consent of the parents. She's lucky it was just slapped. Inexcusable. Just because you're a parent does not give you the right or authority to put your hand on someone else's kid without their permission. There was no imminent danger, and the parents already had control of the situation.