Some aren't, but like MegaTron Bomb said earlier, who really gets hurt in these competitions?
Drew league is indoors, in the time that I've gone to watch streetball, I can't remember the last time someone got seriously hurt during the game, and that's outside.
What could happen is a freak non contact injury, which could happen in practice or anywhere for that matter. The dudes they are playing against show respect for these guys just coming to rep and play with them, theyre not going to be flagrantly fouling them or anything.
