I wasn't saying dogs are demons or even like wild animals. They have been bred to be sociable around humans.
Just explaining why there is often an instinctive fear in some children, that can also carry out to adulthood. In the same way that some people fear other animals that can cause harm to them. In the same way that most of us are not exactly keen on snakes, spiders, wasps, etc.
Of course dogs are an ever common part of our society and we, as parents, should do our best (in the sense that there are limits to what we can do) to teach our children to behave appropriately around them and/or not to fear them. I have done that work with DS.
However, and hence my posts, it is also necessary that some dog owners (e.g. the OP) realise that it is not easily controllable.
Surprisingly, children also need to go 100s of feet away from their parents, run loose, even though they may find dogs (it's a risk they will have to take). It is appalling that apparently a child on a bike should be kept from a safe cycling area (maybe he/she should have been riding on the street?), and restricted to the immediate proximity of their parents, because there might be dogs around, but a dog supposedly has to be off the lead to exercise.
The fact is that a dog will always be intruding on human territory, never the other way around (except their own homes). There is no way that a dog's exercise regime takes precedence over a children's need to exercise and to freedom. (not saying that dogs have to be reined in all the time, but don't bloody complain when you encounter a scared child, FFS!)
One of the problems is that some dog owners have dogs that need a lot of exercise and long runs but don't own large private areas for those dogs, nor can keep up with their dogs running so that they can control them on a lead while they run. A friend of mine has managed to take his 3 large dogs on a lead while running on a bike, so, it's possible to keep dogs on leads and exercise them, and control them and not entangle the leads, just as long as the owner knows what they are doing.
And having a dog that has cured 1000s of children of the fear of dogs means nothing. Some people use their snakes or spiders to cure people of their fears.
My DS is very familiar with our cat. Our cat doesn't bite or scratch (apart from a specific play). DS still screams when he's jumped on, or sometimes if the cat runs towards him, because of the surprise factor.
For all we know the child in the OP suddenly saw the dog, may have perceived some threat (even though it was probably not there) and screamed. In some cases there is no amount of "getting used to" that will prevent a child from screaming.
Live with it, OP, as people who are not keen on dogs have to live with the fact that our towns and spaces are full of dogs.