Territory and Municipal Services - Fenced Dog Park
It would be nice if you didn't delete your posts so we can all make our own assessment of your question, and not guess based on other people's responses.
In most states (not sure about the ACT) it is illegal for dogs to harrass other dogs, people or animals whether or not physical harm is done. In practice this usually means asking before a person lets their dog get in another dog's face, but this doesn't often happen at dog off lead spaces - as most owners assume that all dogs are fine with the direct greeting approach or they wouldn't be there. This is unfortunate and really really common.
But in the ACT - dog park (fenced dog parks) ettiquette is no toys- because some dogs get grumpy if they think another dog wants their toy and the rules are to minimise the chance of fights. It's not about being "right" or "fair" it's about minimising the chances of dog fights and injuries.
Most people I know with highly trained dogs - do not go near fenced dog parks, and some avoid off lead dog spaces too because they don't want to risk injury to their dog from rude untrained dogs. My dog is fairly well trained. Will do what your dog does. Sometimes she gets in other dogs way but it's not always deliberate. People aren't always very accurate with their ball throws, and sometimes my dog is playing chasey with another dog and will run through any open space and doesn't notice some other dog on a retrieve line. The best thing about my dog is she is a complete grovel dog and makes every effort to make friendly non-threatening greetings. But she has been known to tell off rude dogs that jump on her without being properly introduced. And I agree owners who think that this isn't their problem are rude. I know several who are not welcome at a not quite fenced dog park I go to - because their dogs went from rude dogs to attack dogs. And another that now has to wear a muzzle at dog club for the same reason.
I think you expect a little too much of your average fenced dog park user and their dogs and it might be for the best for you and your dog if you don't go there to chuck balls for your dog.