"Subjects are importants", well, I'm not japanese, but in my language subjects are everything. You start with them, you spell them explicitly, you clarify them regularly, especially as they change with conversation flow. It's virtually not possible to have such ridiculous misunderstandings unless one party is completely out of it, like, not listening others at all. I do wonder, if it's normal for japanese or author just exaggerates it on a regular base for comic effect. If so then it's...not very funny for me