dogs

I'm in a quandary when I take my kids to the park, 3 & 5 yrs. Some people take their dogs off the leash and it's clearly not an exercise park.
Some run up to my kids in a playful manner but they freak out. To a child it may as well be a grizzly attacking lol. They are fine about dogs on leashes. These recent episodes are starting to piss me off.
One huge playful dumbo came out of no where. I had to try and round up 2 screaming kids whilst myself not trusting it. Even in play mode it could accidentally harm the kids due to it's sheer weight. I thought I would play it cool and see what the owner did. Did squat. She did later say he's playful, would they like to pat him on the leash. That part I appreciated but she should have instantly ran over apologising and leashing the dog. I didn't scorn her but did say in my most polite sarcastic voice, relax, we're not in America and were not going to sue you.
Then today, a toy dog likewise, near a playground full of youngsters. The old lady found it funny. The next one to do it is going to cop a nasty vile mouthful.
I have the utmost respect for those who 'over'/ follow the rules. I've seen some with soft muzzles, and seriously, these dogs wouldn't hurt a fly, pleasant demeanor.
PS: I love all animals and don't blame the dog.