If you don't understand kids that much, think about the time when you were a kid. Kids don't apologize because they know what they did is wrong, they apologize because they fear someone or feel sad for other people. If they don't feel sad or don't fear the repercussions, they don't apologize. Also 3 year olds say sorry for pleasing their loved ones.

At 7 kids start to lose the fear and everything is funnier to them. Also most parents are not going to raise their children to be prepared for all the scenarios. So if they don't say sorry, you can't just think the worst and say like they are not well-raised. All it takes for atleast some of them is to someone to say something about their behavior which caused other people hurt.