What exactly can they do? They have to call these things at speed, while we get to review everything from multiple angles and in slow motion. If they review every call, that'll kill the game. Add more refs, will probably just result in more calls. There's not a whole lot of reasonable answers... it's best to just accept it as part of the game, kinda like the odd shape of the football that bounces a bit unpredictably, sometimes your way, sometimes the other way.