Neither, I believe it is often just indifference. The same as if you noticed something different about a new person you met, but then just carried on interacting with them for whatever purpose you were doing so anyway. I met someone yesterday at work, and I noticed he had an occasional vocal tic, a kind of click sound every so often. I didn't feel empathy or sympathy, I just noticed it and moved on. I was indifferent - it literally made no difference in the way we conducted the meeting. I think it's the same for most people when they notice someone has a stutter. They notice, they might register a bit of surprise or curiosity, but quickly move on to continuing the interaction. I think that's what we mean by "people don't care." It's not toxic positivity, it's just reality. People care much more about the content of the interaction than making a big deal out of some difference they notice.