I know there was some police agency that did supervise the racing scene and also, they let the kids race the squads if they wanted. However, it didn't last that long becuase of the liability. If there were accidents, fights, etc., like there were, then the police agency or city is liable for anything that happens.
There is are many liability issues and different insurance needed for a race strip or even closing a highway. It's too risky. Even though most people are safe, there is always that one dumb sh*t that ruins for everyone else. Look at Red Rock Racing Strip when that was full blown. There were no incidents for like 5 years then within one summer 2 people die from stupidity of spectators. Death is a major liabilty police agencies don't want to bring on themselves.