Not the bad guy
It’s unfortunate, but some parents do this not only with healthcare workers, but also with police officers, and it’s an unbelievably stupid practice. To make a child fearful of the professionals they may at some point need is counterproductive and poor parenting.
If a child is acting up and being disruptive in a public place, a better solution is to remove him or her from the premises until you have regained control of the situation.
My goodness, you don’t have to thank me. Your letter moved me to the point of tears. Although I have printed many letters about pennies from heaven, this is the first time I have heard about a postcard. I’m glad it gave you the comfort and validation that you needed.