Why is it so hard for someone to apologize?

Do you know anyone like this? I have a neighbor that blames his problems for everyone in the neighborhood. I have a steep dirt bank in my yard surrounded by fencing that s up next to it so MY dogs do not get out of my yard, my neighbors dog comes down this bank to visit My dogs to which then the dog is in my yard. When he goes out calling for his dog, it does not go home because he is stuck in our yard, plus we live a bit away from the neighbor so his dog cannot hear him getting called. My neighbor then drives to our house to pick up his dog, he lets me know how unhappy this makes him. Gee whos fault does this sound like? He asked me last year to keep my dog out of his yard, so we built this fence, my dog no longer goes into his yard, but I go through this? This happened yesterday again, this time I said something to him, I told him this is not my problem and he is rude. He came back with "When I come down to get my dog he is fenced in your yard". He knows he is wrong, does he apologize has he apologized to me for any of the rest of the crap he has so rudely done? NO, why is this?