I don't see the reason for her to be cuffed, going with the commentary. I hope the cart was cuffed to her car for the sake of the video as she was released moments later.
Yes, she was dumb. But a minor scratch, if anything, isn't worth that reaction.
That's one reason why I carry zip ties big enough to be used as cuffs - paint won't get scratched when somebody does a stupid and I can attach several carts to the vehicle in seconds.