In "Joey Gets Tough", why does Joey punish DJ? Why does she think it is unfair? Why is she angry that everyone is siding with Joey instead of her?

I think the reason is Joey is the adult, he needs to be able to tell the girls no. He can't keep letting them get away with whatever they wanted. DJ, I get why she was upset but she also didn't tell Joey that she was going to be late and what she was doing after her karate. She was still a child and she needed to learn that she can't always get her own way.