It’s difficult to reply when you don’t say what the difficulties are.
So from what I can make out your dog is reactive to certain situations. No idea what (because you haven’t said).
If my dog hadn’t been socialised to the noise from traffic, for example. I wouldn’t expect her to walk along a main road with traffic passing. What I would do - and have done, many times - with a “rescue” dog, is sat on the pavement, adjacent to a main Rd and kept the dog close. Every time a bus/lorry/van passed I spoke to my dog telling her/him “It’s fine” and gave her/him a treat for not reacting. Giving a treat conditions the dog to think the “scary thing” = a treat. Eventually (and it doesn’t take long) they will associate traffic noise as being a good thing.
Exactly the same psychology is used when getting your dog used to screaming kids, joggers, inquisitive, rude, off lead dogs, teaching them to walk past people/other dogs, tricks…. Dogs need to be desensitised to anything they fear. You need to be more exciting than anything your dog will encounter and encourage them to always be close to you. Because you are the greatest, most exciting thing…. So much more exciting than the out of control dog that is heading towards you, because it’s owner hasn’t taught it recall. Your dog should not move toward the random dog. Your dog will want to stay close to you… and does, because you are the best thing ever and will always trump some random, out of control dog. And your dog will be rewarded for sticking close. Get it?
Some dog owners think throwing their puppy into a group of dogs to run around is socialising them. Nothing could be more damaging for the puppy.
Any behaviour you expect from your dog will happen with time, patience, clear instructions and loads of high quality treats - my dogs will do anything for cheese!
I lose patience with dog owners who’s dog lunges, snapping at my ankles, when they allow their growling, snarling, on lead dog to get in the face and snap at my dog when my dog is sticking close to my heel, ignoring the snarling dog. They they use the excuse “He’s a rescue dog. I rescued him”. (Aren’t I wonderful 🙄)
The poor dog is set for a life of being shackled because the owner who “rescued” them has done nothing to enrich the dogs life. But you can guarantee they will be the first to complain about dogs being walked off lead - even when the dog has no interest in the dog or it’s owner.
Anyone who is nervous about running around off lead dogs has good cause if the dog approaches them or their children. A well trained dog won’t approach anyone.
I am more concerned that people think it’s ok for their child to stroke an on lead dog. No! They are on lead for good reason. They may be on lead because their owner hasn’t bothered to teach them a solid recall but, personally, I wouldn’t take the chance. Most dogs I know who are walked on lead is because they are nasty and will take your hand off given the chance.
There’s not a chance I would allow my dog to approach an on lead dog for fear of him/her having his/her face taken off.
Give me a boisterous, out of control, friendly off lead dog anytime before a vicious, out of control, on lead dog (as much as I hate being jumped on by random dogs).
A dog may be on lead. It doesn’t mean it’s under control - especially when on the end of a bloody useless, dangerous retractable lead!