Now that's the million dollar question! As near as I can tell the short answer is it takes too much time and too many resources to investigate gaming sites. Project Safe Childhood has identified numerous sites where children are at higher risk of being approached by a predator and have publicly stated numerous times that online multi-player gaming is the number one place for internet predators to find victims.

Assistant United States Attorney Frank Williams, the Project Safe Childhood coordinator for the Northern District of Florida has said of multi-player gaming:

“The wolves know what pastures to go in, they know where the sheep like to play. They know there's no shepherds there. They know they can find addresses, their school.”

And yet law enforcement continues to perform stings on adult sites where there is absolutely no reasonable expectation of finding a child much less a child predator. According to them the real child predators hang out on adult websites going through hundreds if not thousands of ads and profiles just on the off chance one of them might be a minor child posing as an adult.

Its because law enforcement knows that only horny sexually active over 18 yrs old hang out on ADULT websites and chat rooms.
They also know its more fun and less time consuming to hit up a lonely guy late ay nite posing as an underage teen looking to "experience what its like" with an older guy.
no..lets not go websites where its a known predator hangout. Hell that takes intelligence.