In my experience it is because they honestly do not believe they were wrong.
I believe it is all three, usually with one predominant depending on the situation.<br />
My philosophy is that saying "I'm Sorry" costs me nothing, whether or not I was at fault, and can have a tremendous up side. To me, positive enduring relationships are far more important than my pride, righteousness, or insecurity. <br />
I know who I am and am proud to be who I am. I understand that I am sometimes wrong and far from perfect. Even when I am sure I am right, I recognize that sometimes I am wrong and that righteousness is false.<br />
I am secure in my strengths and abilities and secure in my ability to do what needs to be done. I recognize that there are other people in the world who are better than I am in some ways -- smarter, stronger, younger, wealthier, more attractive, and so on. I also know that none of those things make them a better person. Therefore, I am secure in my identity.<br />
A person lacking honest and ob<x>jective self awareness is likely to suffer pride, righteousness or insecurity and therefore find themselves unable or unwilling to say "I;m sorry."
They are not sorry.
Because they are not. Brutish, Barbaric, Without Conscience
They can't simply swallow their pride:(
all of the above amongst, cockey, stubborn, bull headed, just plain ignorant, maybe their not, childish, disrespectful, ashamed, insecure, I Quit..