Islam teaches Muslims to police other Muslims.
In Singapore, the Muslims here already quite mild. I have Muslim co-workers and friends who each pork. Each time they do, they have to keep watching over their shoulders, ever fearful that other Muslims, including strangers, will want to step in and kick their ass. I have a Muslim lady coworker who does not wear tudung, and she sometimes says she gets hell from her family and friends to put it on. It's a recent phenomenon as Muslim women decades ago hardly wore the tudung and other Muslims couldn't care less.