it's not just matchroom, this is all WPA events. the first one darren was tested at was at the CSI/predator 10-ball in vegas. i'm pretty sure the TD's are glad the WPA handles the testing so they themselves don't have to constantly ensure the sobriety of a field of 256 or 128 players.
the thresholds for THC are too low in my opinion, but that's another issue. the main problem here is the methods, which obviously were disruptive for the player. one can suspect they know very little about pool if they directly approached a guy who just lost 11-10 in the latter stages of a major tournament. i really feel sorry for darren here, despite the outburst. i hope this doesn't effect his sponsors, he has videos with millions views on his youtube channel and he's always displaying his sponsors.