Sometimes it's just hard
My first dog was a reactive byb German Shepherd. I did cadaver search work with her as an outlet, and that community was incredibly accepting. Many people worked spicy dogs, so there was only ever one dog out at a time, and on leash moving between areas at a conference or whatever people were respectful and didn't let dogs run up on each other. We didn't make it very far as a team. She was naturally very handler focused, and I was a terrible handler. We failed our first attempt to certify rather dramatically, and I found out she had hip dysplasia, and I started a new career, and well life happened, and she became a wonderful pet for many years. She loved all humans, was incredibly responsive off leash, and generally was a great dog to live with. Still, it was hard not being able to take her places where there might dogs in tight places or inconsiderate/oblivious owners. Watching her age with hip dysplasia was also really difficult and not something I would wish on anyone.
When it came time to get a puppy, it felt like a chance to do everything right and get a confident, healthy sport dog and adventure companion. I still wanted erect ears, but I wanted health and confidence and a smaller package to be easier to take places. Every rat terrier I had ever met was outgoing and ball crazy. I looked for breeders and found one that was highly respected. Her fb page was filled with the kind of dog I was looking for - hamming it up at a conformation show, crushing it on the agility field, relaxing under a cafe table, hiking and backpacking with their people.
Fast forward a couple of years and now I have a reactive rat terrier. He's reactive only in the literal sense of overreacting vs the colloquial sense of aggressive, but it's still something I have to work on and think about every time we go anywhere. We joined a rally class to learn how to function around other dogs, and he did so well my instructor convinced us to enter a trial.
Turns out rally is NOT an accepting community for spicy dogs. The whole venue was crowded and chaotic and way beyond what my dog and I were ready for. We still gave it our best shot, but he was over aroused and unfocused. We were supposed to go fast toward the ring gate and do a U-turn, but I completely lost him on the go fast (my handling didn't help) and there was a dog on the other side of the gate right at the U-turn that he barked at. We were invited to leave and not come back ("I would never tell someone to scratch... I just wanted you to be aware that you could be DQ'd... not be allowed to do any dog sports... it's an optics thing... it's up to you").
I see the people who don't have to care. The people whose dogs walk through a crowd confidently. The people who stand in a queue of dogs and chat with each other instead of paying attention to what their dog is looking at and what he's feeling. The people who join group classes and listen to the instruction with their full attention because they know their dog is fine.
I'm still trying. My dog loves to train, and when we're on point, he's absolutely gorgeous. I alternate the fun classes with the behavior classes so we can mix in some things he's good at with the things he's not. We do scent work around the house and when we travel. We hike on a long line. We run fast cat. We practice seeing a dog and giving attention. We practice relaxing. We practice doing challenging things in small slices to build confidence. He's making progress, but sometimes it's just hard.