You need training. The people who will not let you near their dog are doing it right.
Hope you can find a trainer in your area and please do not let your dog meet other dogs on leash even if the other owner is ok with it. This is bad socialization.
In my opinion the world would be a better place if people got over their desire to let their dogs socialize with all the dogs they see on leash while going for walks. It should be about you and your dog.