Haven't read the thread yet, but:
Ten years ago, when I had a baby in a backpack, and two small DCs on foot I would have agreed with you. I had never had a dog, and knew nothing of them, other than that they scared me. I have made several comments over the years just like yours.
In the intervening years I have acquired two lovely, gentle (but quite big and quite loopy looking) dogs.
But let's look at the facts shall we?
The 'bear' sat down, to wait for its owner, and then stepped towards you?
How dare it.
Did it growl? Was it in any way 'out of control'? Frothing at the mouth? Did it seem agitated? did it jump up to rip your child from your back? Or was it just a dog not a leash that made you feel nervous for reasons you can't quite put your finger on?
I have learnt, as an owner, and as a bystander, that if someone says 'Don't worry he won't hurt you' they mean it. If a dog is an unpredictable danger around people or other dogs, generally speaking the last thing the owner wants is a bloodbath/stressful scene on their hands and they don't allow the dog to go ahead for a little play around approaching members of the public with babies.
I agree, that you don't have to take them at face value - that is your choice. But unless a dog is being actively agressive or intimidating, (and a lesson in awareness of dog body language would be useful here) I think you need to relax and assume that all will be well until you see real signs that indicate otherwise.
Whatever you may think, it is not illegal to have dogs running free, only to have an 'out of control' dog -ie one that is a danger. They have the same right to run around and enjoy life as your children do - so long as they are not hurting anyone. And they were't were they?