Dog owners and dog culture in AKL

I was kicking a ball in the park with my 4yo son. Dogs are not allowed in that park. One big dog starting to run towards us, not aggressive. My son doesn't like dogs and I don't feel comfortable having dogs bigger than my son around off-leash.

I started to ask the owner to hold the dog while she was casually walking to us with her friend. She came over and said that it wanted to play with the ball. I replied that my son doesn't like dogs. She put it on leash and started to walk away with pretty unhappy face.

Once she was 15m away I said that "you are supposed to say sorry". She replied that "you gonna cope without it. Teach your son to like dogs". I said that she needs to teach her dog to listen to her commands. She said "go fuck yourself". I replied "fuck off bitch".

She turned around and started to go fast towards pointing her dog towards us which looked in the moment as if they would attack us. I started to shield my son but luckily owner's friend shouted asking to back her off. She kept walking but stopped eventually and walked away.

What's the actual fuck?! Did you really want to attack a 4yo?! What's wrong with people?

This is not common, usually people say sorry and put them on leash. But sometimes when I ask people to hold their big dogs because my son doesn't like/afraid of dogs I get a similar reaction from owners.

What am I doing wrong? I'm not telling your dog is ugly, I'm not saying you're a bad human for walking a dog. Why do you believe all people must like and be comfortable around your dog? Please help me understand.