It's not feasible to do a real "Lord of the Flies" experiment on purpose; not even the notoriously sociopathic world of reality TV producers could get away with that.

If you have adults watching and ready to spring in at a moment's notice, the kids will limit their behavior to what they think they can get away with.

If you don't, there's a good chance someone will get seriously hurt or killed.

Not surprising that they (or maybe their underwriters) picked the first option.