I don't understand: Saying Sorry

Second in a series.

A few times in the last month, some mother at preschool has come up to some other mother at preschool to tell them that their child hurt or offended their own child in some way. Today it happened to us. A girl a bit older than the girls told her mother that Miranda stepped on her hand. So then they came over to us to tell us. I asked Miranda if she did that by accident and Miranda immediately said yes and continued with "I said sorry to her, but she didn't hear me." I asked Miranda to tell her sorry again. Which she did. The mom said thanks and they walked away. Miranda went on to say that she wanted to sit next to her at second circle time, but that she wouldn't.

I think that whole situation is lame. Miranda did the right thing on her own at the right time. I don't think she should have had to say anything again, but had I not done what was expected I would have looked like the insensitive mom. And why didn't the other mother make her child say sorry for being mean to Miranda at second cirle.

What is up with all that?