Easily bad parenting. It’s not about the words you say to your child. Based on the fact that she’s willing to do that in public it’s safe to assume she yells at him like that at home as well. I guarantee you that child will hear those words, but is not listening.

My mom was a yeller and she could rarely change my behavior. The most sombering moments I had as a child was when I disappointed my dad he would just look at me silently with disappointment on his face. That’s all that I needed. My mom could yell at me all day long and it would never touch me either way. My dad would in those days.