I think a pilot doing a demo is mainly concentrating on the display line and crowd centre. Maybe overlaying a 'normal' plotted path might give overflight warnings, but avoidances are likely to break the rhythm of a well rehearsed performance (?)
Avoiding populated area overflights might give compliance with the 'good taste' aspects of a safe display, but accidents diverge from the planned flight path. A catastrophic birdstrike could put the column of greasy smoke anywhere. An FCU/linkage failure would stop the plan in its tracks and mandate a direct dart back towards the field.
i think most car accidents happen within a mile of home. Most air display accidents (very very few) happen near an airfield and big crowds and jammed roads... Over the sea displays would plaice an unacceptible risk on fish stocks.