I think you're forgetting that within the police force there are various divisions that are assigned to do different tasks ie. traffic, major incident etc.
We only hear of the guys "doing over" hoons because I'm sure most of us don't come into contact with the other police departments. So one group is doing their job, another group doing theirs etc. It just so happens that one group's work affects us, and another's does not. Therefore I think the general consensus amongst hoons that the cops are spending all their time targetting them is quite unfound.
I also think that on the whole the cops do a fine job as it is. Yes there are those that are arrogant and a bit pig headed, but perhaps you have to be when there are so many back-chatting little pricks out there.