W..
Pull ups are the spawn of satan.
You've done the literary equivalent of teaching him to read, giving him cliff's notes but then wondering why he doesn't want to read shakespere. Or teaching him to cook, showing him how to order food and then wondering why T'giving is deli turkey and instant taters!
Pull ups are gone. Convenience = lazy. If he has an accident he has to clean himself up - no rewards (the reward is dry pants and no cleanup), no punishments, no scolding. Simple natural consequence.
You have to train him that he has to do it himself.