You don't have to tell a kid to their face they're an asshole. Do you not have a filter at all?
Kids in general can't be expected to act like adults because their brains are still developing. They also lack experience to inform their actions. Some seem like assholes because of these factors.
It's just important however to realize that some kids are assholes. No matter how you humor them or mollify them, they'll still be assholes. After trying to humor them and understand them if they turn out to be assholes you can just deal with them (or don't) like you would any other adult asshole.
But it's pretty unhelpful to the children if you give up on understanding their problems like that and just label them bad.
What are they going to better after you call them an asshole.