It's never nice watching a child being shouted at but I'm sad to say that a lot of us do it at times.
I remember when my dd was 4, she kicked a shoe fitter at the local shoe shop, on purpose because she didn't want to be fitted.
I totally lost it...and this is a child who rarely got shouted at, so I'm screaming at her like a banshee, telling her how unreasonable her behaviour is and how ashamed I am of her.
She's weeping, completely heart broken and I just couldn't stop yelling. It took me ages to calm down. I just couldn't figure how to make her see what she'd done was so wrong...I went over the top.
I'd be mortified if I saw someone doing what I did, but it was a one off.
With the parent in question, who can say? It may be she was at the end of her tether. She might use that kind of language with her child every day or she might just be a bitch. You can guess, but you can't generally tell on one hearing.
YANBU but it's a sad fact that parents (a) snap occasionally and (b) sometimes fall into the habit of shouting at our kids (not that I think I have, but I couldn't judge someone who had).
Poor little mite....