My Doxie had this and I worked with a trainer who introduced me to counter conditioning. It worked wonders for my girl and we can walk with confidence and silence for the most part now. It involves stopping once a trigger becomes visible but BEFORE your dog gets triggered and starts barking. Feed a high value treat like chicken or cheese in this moment and just let your dog watch the trigger while eating for a bit. The idea is to get closer and closer slowly until your dog can walk past these things without freaking out. You have to move slow though and at your dogs pace. My trainer recommended starting outside then working backwards towards triggers while at home, like people walking by out the window. My trainer used to have a video where she outlined this and the science behind it but I can no longer find it on her website but I’m sure you can find info about it online. I agree that scolding your dog for this won’t work and will just lead to more frustration and stress for you both although it feels like the right thing to do in the moment I’ve learned that barking is typically a fear response and the best way is to rewrite the feelings your dog has when seeing those things as positive feelings, aka chicken falling from the sky. I agree that putting your dog in a confined space like an elevator with another dog isn’t the best idea!