Like I said MOST choose flight so I would not worry much but learning to read there body language helps. More times than not slowing backing out talking is all that is needed to defuse things or standing your ground talking
All the black bear stories you mentioned minus the one in camp I experience similar encounters multiple times a year but mostly when I am hunting them or choose to mess around with them. For the most part unless the bear is wounded I have not felt the need to shoot out of self defence but there is the odd jerk bear and they don’t carry signs
Good habit is to have your rifle ready before you yell/talk at a close up bear because they can cover ground fast. Another good thing most should practice is close range instinct shooting. Try to hit a paper plate at 20yards without using scope/sights quickly. My mentor I learned to bear hunt from preached learning this skill.