600Kbear, Reportedly, the Rev. Sun Myung Moon did not randomly match up his mass marriage participants. For one mass marriage involving 35,000 people, he personally made the matches himself over a two month period by scrutinizing the applications and photos of those involved.
His followers believe that he has the ability to correctly match destined mates, sort of like a super-shadchan.
Also, most of those mass-marriage figures were inflated. Many of the participants were already married, and were just renewing their vows.