Back in the Boy Scouts, at summer camp, myself and a couple friends snuck out one night after curfew to commandeer a couch someone had left by a dumpster at the other end of the camp (maybe a half kilometer away).
Now, our particular designated adult was a very stick-to-the-rules type, so we definitely did not want to get caught. I, therefore, made my way slowly and sneakily. The summer camp was in the woods, so I’d keep myself behind trees and bushes and out of the light anytime someone went by. At one point I literally hunkered down in a ditch, staying below the line of the headlights of a passing car. At another point I was maybe five feet from a guy, standing in a shadow, entirely unnoticed. It was slow, but a very fun game, and I was not noticed.
… and then I arrived to find that my two friends had done the walk much more quickly. They didn’t bother hiding at all. They just… walked over. Nobody particularly cared. Sure, our curfew violation was salient to us, but nobody else out that night was paying any attention to us. Why would they?
What I learned from that experience is that nearly everyone is, by default, invisible to nearly everyone else nearly all of the time.
If walking among strangers, it takes really quite a lot before anyone will pay you any attention at all. It’s probably not going to happen by accident, at least not to you. It certainly isn’t going to happen by sending subtle signals of any sort; zero of the strangers will pay attention to any of those.
The ancestral environment was… presumably not like this. Our ancestors were probably surrounded by strangers to a much lesser degree, and therefore were for less invisible. Our brains are probably not calibrated to the degree of our own invisibility, in the modern environment. That can cause emotional difficulties.
People relate to invisibility differently. I tend to find it comforting, safe; an invisible person attracts no threats. Other times I find it freeing: invisibility means I can just do stuff, and nobody will say anything or even pay attention, even when I do things which feel blatant to me.
… but on the flip side, for many people, invisibility feels like nobody cares. It feels like being unwanted. Like nobody being interested in you at all, like nobody would notice if you disappeared. And yeah, that’s all true to a pretty large extent; most of us are surrounded to a very large extent by strangers who mostly don’t notice us much. Personally I recommend making peace with it and finding a way to enjoy life anyway, but that’s harder for some people than others.
I suspect that a lot of people flinch away from their own invisibility. They feel the pain of “nobody notices you enough to care” (and the comfort of safety and freedom is not as salient). And then they tell themselves whatever story they can, to pretend that more people care more than they actually do. And one side effect of that flinch is to vastly overestimate the extent to which people notice when we Just Do Stuff.