Even if someone has experienced trauma, and even if they developed PTSD from it, I think there's still a possibility that they won't "get it" until an expert explains it to them, over and over also?
It isn't that others don't care, it is that this disorder isn't "rational" to regular thinking. That those with PTSD also have a tendency to forgot that it's because of the disorder that do thus and thus...

shows that it must be extrement difficult for others to remember also.
I wish people who like to pull practical jokes, and also scare people would realize that not everyone enjoys such behavior.