I have a very recent personal experience of this - last Sunday I was with my daughter in a park running behind her as she whizzed about on her very first brand new bicycle. There was another girl of a similar age coming in the opposite direction, and as they swerved to miss each other their respective stabilisers got caught up in each other and both crumpled into a heap - I helped my daughter up first (well, you would wouldn't you) and then helped the other girl up.........................and from across the park came a sprinting woman screaming at me, literally screaming at me, to leave her daughter alone.
I tried to explain what had happened but by now she was verging on hysteria, so I beat a hasty retreat with, what felt like, about three dozen pairs of accusing eyes on me.
So, would I help a child again in a similar situation?
Absolutely not.
If that meant leaving a crying, hurt child on the floor, then so be it.
Shame.