Would you have said something to this woman?

This was many years ago, I was 18 at the time and on vacation with my family. I had to run into Walmart to grab a phone charger and I was standing in the checkout line in the electronic section. The lady in front of me had a daughter probably about 4 yrs old...she had something in her hand she wanted and her mom took it from her and put it back. The little girl started crying (nothing obnoxious) and her mom pushed her face against the counter so that her nose was against it and told her to stop crying. The girl was trying to stop but she was still sniffling so the mom smacked the back of her head (nose still pressed against the counter) obviously hurting her and causing her to cry again. I immediately saw red and called the lady out “how would you like it if someone smashed your nose against the counter like that”??? She told me to “mind my own damn business, it’s not your kid”. I didn’t say anything else because idk what kind of backlash it would have caused for that poor child. They walked away, red nosed and engulfed in tears. It still eats at me to this day. I wish I would have done more but I’m still not sure if I could have?