I guess thats why the C over D model is used. The class C will be used to a lower level than previous designs, (and is already rolled out around the country) then the tower looks after a more limited amount of Class D, most of which can be identified visually, with the help of a TSAD (or similar).
At the end of the day this is about get risk to ALARP. Sure, you can go the whole hog, but if that model is only used in Ballina it needs to be rolled out everywhere and the cost is simply prohibitive and really, not needed IF the ALARP is quantified and accepted.