Why doesn't Kled's passive work on jungle monsters?

Riot's statement is that they didn't want him to be able to just easily farm back Courage come late game by just running into jungle and killing said jungle monsters near instantly (since anyone with items can do that at late game) to get Skaarl back super fast.

well, you don't really need his passive after level 3

you just need to rush w and instasmite the krug to stay alive before that

What nep2une said.