How do you feel about parents who can’t control their kids?

Wasn’t working this time, my dad and I were waiting in line and there was a woman with two kids who were acting up. The older one seemed quieter, except for smacking the younger one. The younger one kept yelling, hitting the mother, throwing her phone, etc. I’m used to children yelling since I work retail, but my dad upon leaving complained about having a headache now. Was just wondering how it looks to other customers, workers, and parents?