I am pretty sure that I am not bu but interested to know what others would have done.
Dd (12) went to a meal out for end of season sports. Her team all sat together, parents on different tables. Everyone had a good time, running in and out to the play area, all fine. At the end of the evening I was looking over at dd to see if she was ready to go. She didn't see me, but started picking up peas and flicking them at people's plates. I was mortified and called over "dd stop that. Don't throw food!" a couple of others started doing it too.
The parents who I was sitting with said oh let them do what they want and gave me a filthy look. I was pretty taken aback tbh.
I only told dd to stop, not any other child.