I must be an unusual person in some respects (aren't we all in our various ways).
I think that it must be that I observe more than most. Maybe its due to being an extreme introvert, or years of looking at birds picking out small details to identify them, or being a visually oriented person, I don't know.
Its true though, and it comes across to me very strongly when I am out in public. Comparison may be generally foolish, but in this case, I can see differences between this entity "me" and others. Especially in grocery stores but again today when I am in a car dealership waiting room. I was there 2 hours and it is interesting to observe people. One man was engaged in intense conversation with a woman - I don't know if he just met her or if he knew her before. My impression was that they did not come in together, but I don't know. Some people plainly prefer to stand rather than sit down. Some people must be occupied - in fact most must be occupied. Most were reading, some had laptops, some were listening through earphones, etc. I was not exempt from this either - I was reading my Kindle. I was reading until a man sat himself down next to me, opened a device of some kind and started playing a video game on it - unfortunately one that had sound effects. I thought - how is it that this guy doesn't think that this repetitive sound of electronic explosions isn't going to disturb me? I obviously think too much.
I don't know why I find it so fascinating but its a fact that people just don't pay any attention to what is going on around them. They don't look at all. I almost can't get over this - it is bizarre. Granted I am not 100 percent aware either all the time, but the degree to which my fellow humans are tuned out is amazing to me.