If SECURITY & VIGILANCE cannot fire, then what good is the patrolling carried out by SECURITY & VIGILANCE?

Firing in a densely populated city like Karachi, can be seriously double edged. The risk factor does not permit asking a non-governmental body to fire; as it can have serious legal complications. Nevertheless, SECURITY & VIGILANCE in coordination with Rangers / Police, patrols the areas, because whether fire or no fire, presence of SECURITY & VIGILANCE still deters criminals; to at least wait for any patrolling vehicles (whether Police, Rangers or SECURITY & VIGILANCE) to leave before the crime is committed.