That seems to be contradictory. How is “misbehaviour among girls is typically (though not universally) less prevalent than among boys” when “Girls have tended to both misbehave more and been punished more severely and readily when they did so – than boys”?
Possibly – but more likely, it was just understood that corporal punishment was less useful and less effective with girls regardless of the school they were in.
Probably because it was intended to be less effective with girls by only being used when it was unlikely to work. The same “commonsense” that told them it wouldn’t harm boys, but would harm girls, would have told them that.
You put it stronger that I. Exempting girls from CP is an indicator that it’s being abused. In such schools, it couldn’t be used as a punishment for any particular offence because half the school could commit that offence yet not face that punishment.