High speed chases are generally carefully thought out, even at spur of the moment. It all depends on the time of the day or night, the fact that it is a felony, and important the the criminal be captured now. It also depends on how heavily traveled the street in question is. There would be no high speed chase on Main St. in the middle of the day.
The same question holds true for an ambulance: the rush a person with serious injuries to the hospital at high speeds, as well.