>generally understand and care how they are perceived

Personally, I do care how I am percieved. I want to be a legitimately good person. However, we sometimes do things that make it look like we don't care what others think of us because it doesn't always occur to us that what we are doing isn't normal. Even when beforehand we think of what a normal and appropriate thing to do might be we could totally miss the mark and do something weird that gives the impression that we don't care.