That was the first thought that crossed my mind.
If they're all so confident that they're the 'good' type of dog owner and their dog is well-trained and isn't a problem, then why didn't they all bring their dogs with them?
If they're all so keen to prove that their dogs are safe and not dangerous, this would've been the perfect opportunity to prove it.
The fact that they couldn't/wouldn't bring all their dogs with them speaks volumes. If even all the 'good' dog owners know that their dogs can't be trusted 100 per cent to be around other dogs and lots of people, that says it all, really.