I don't think there is much we can do. Some people just push the limits too far and don't realize until its too late. Maybe some sort of screening process would help. A big problem is inexperienced riders trying to keep up with faster guys by riding reckless. If you had a staggered start where the experienced riders started first then the inexperienced riders started second then maybe inexperienced riders would be less likely to get baited into keeping up with experienced riders. Different checkpoints for different levels of riders could send less experienced people on safer routes. The biggest thing that could be done would be to stress safety over speed but we all know that some people don't listen to that kind of stuff. Those are my suggestions to help newer riders. All of those suggestions are probably already in use in some alleycats.

Let the messengers and big shots keep doing what they are doing. Its sad when people get hurt/killed in races but it is ultimately the doing of the rider. We all know the risks associated with street racing. If it wasn't dangerous half the racers would quit.