"Your child..."

So Knuckles is playing outside, and I don't hear any screams, so I assume everything's OK. It took the installation of a double-cylinder deadbolt and three days of grounding him every day, but he finally learned that he's not to go more than 3 houses up or down the street, and he's being rewarded for his obedience by being allowed to play outside. Then I get a knock on the door. It's a neighbor lady with whom I'm not acquainted, who's come to inform me of an incident in which she believes Knuckles (who is happily riding his Hot Wheels in front of our house, completely uninjured) was about to be run over by a hideous evil car. It doesn't add up to me the way she's describing it, so I politely say "Thank you for letting me know." She then goes on to repeat her account of the incident half a dozen more times, and each time I say "Thank you for letting me know." After the first few times, I start implementing some conversation-ending body language, because Sonshine came home sick from school and is puking, and the point of sending Knuckles to play outside is to enable me to get some work done inside. Finally I got sick of her not backing off the topic, so I pointed out to her that she'd said the same thing half a dozen times and asked her if there was some particular reaction she was trying to get from me. She said no and then yanked her child off Knuckles' old ride where he'd been playing happily with my permission, and left in a huff as she told her child he was not to play over here, loud enough for me to hear.

So what just happened here? What did she expect me to say to her incoherent description? "OMG THAT'S SO HORRIBLE! I'm going RIGHT NOW to build a time machine so that I can go back in time, hover over my child till a car comes after him on purpose, stop that evil car in its tracks with my Super Strength, pull the driver out of the car and beat the living snot out of him!" What am I supposed to do? I can't undo whatever incident she observed, nor do I have the power to get her to express herself coherently, and her outrage at it doesn't make my chores or sewing get done. And I'm not going to swear a promise to do better to look after my kid to a total stranger who can't even be bothered to state her name, so what did she expect?

Is this the new, modern social skills? You go over to strangers' houses and, without even introducing yourself, try to get them to admit something? My Aspies have better social skills than this, but they have been trained. So does that mean there's nobody training the normal people?