That is such an excellent and helpful clarification about reactivity and whether to use the e-collar for it. And pitiful that Asha would flatten herself in anticipation yet not be able to help it. That hurts my heart for her. I think some of the time that is how it is for Daisy with cars. I'm not sure she can help it SOME of the time. I have to keep in mind that I have seen improvement, and I definitely have, but that's hard to keep in mind when even with the prong collar on she is lunging and acting like a complete lunatic and embarrassing me in front of my neighbors who are just driving down the street. I haven't walked her on the leash at night but a couple of times and when I did a few days ago it was even worse. No more nighttime walks until that is better in the daytime.
Good advice about keeping the muzzle training a game, which honestly, I stink at

I will try. I tend to play when I'm thinking of it as play time and no nonsense about the "let's just do this" stuff. I don't really know how to make that a game. The only time I want to use a muzzle is a new person entering our home (just until she calms down some) or taking her to the vet. When we went for her recent visit the vet had me put a muzzle on her (one they had) before he sedated her for stitches (because of how she reacted when he walked in the room). It was their closing time or he might not have been as quick to recommend it, but it made me feel better too. It has been several months prior to this since she had been to the vet and the time before this she calmed down after a minute (although still wary) and they were able to give her shots with me holding onto her comforting her, keeping her attention on me. On this day for stitches, even if it hadn't been about stitches, she was more amped up, not sure if it was because she was injured (she otherwise seemed completely unbothered by it though) but I think it was more about that she has just gotten more reactive to people over time than less. She has never had a negative experience so I don't understand why that is other than she doesn't get enough practice.
For walks, we can easily just keep our distance. I try to be 15-20 feet away (that seems to be what she deems a safe distance) and she mostly, now, doesn't react at that distance. Most people , if they try to walk closer, they change their mind, no muzzle needed.
A few days ago, one of my daughter's friends came over. This friend had not been to our house since we got Daisy. Daisy does lunge forward when she barks very loudly, with the hair standing up on her neck, and its not a true growl, but a growly kind of bark if that makes sense. This friend has Down syndrome (so she has some cognitive disability) as does my daughter, and I wasn't sure if she would be overly afraid of Daisy, so I had her on the leash, which I feel pretty sure made her reaction worse. This friend spent the afternoon at our house. Daisy would smell her and a couple of times licked her but react wildly again if she dared move. I did crate her for a short time and I stayed in another room with her leashed to me with the door open some of the time so she could hear that our guest was still here. I could not go about the things I needed to do in the house. I knew that when I would be taking the friend home, Daisy would be crated for a few hours, so I didn't want to crate her all afternoon but I was then completely unable to do anything I needed to do. Daisy would react every time the friend got up to move around the house. Her reactivity really did last longer that day than usual and I feel like the leash was at least part of the equation (maybe the whole reason) but I sometimes don't feel 100% sure she won't get scared when the person moves and then bite before I can anticipate it. I felt like a muzzle would help me feel safer about letting my guard down just a bit.
I am 100% open to trying whatever you tell me might work

The way you described getting in Asha's face, that you had enough, that is how I felt that day. I was able to start fresh after a few hours away from home, but, man, I was fed up with her. If I say this person is OK, she IS OK.