<< The courts would soon be cluttered with appeals and you would find yourself having to defend the accuracy of your speedo on every occasion that it was used as evidence… >>

I can’t see that that would be the case Is Mise.

Anyway, being able to prove the exact speed that you were travelling at would I think rarely be of particular importance in amongst the other photographic evidence of rank driving.

Afterall, there is no excuse for tailgating or dangerous overtaking or whatever other stupid driving antics that your cameras might have recorded.

There is a slight problem, you will need multiple cameras etc., to record every thing at all angles.
Unmarked police cars and obvious police cars equipped with cameras etc., are no deterrent, nor are the police aircraft that can monitor roads.
The only proven deterrent is plainly identifiable police cars driving along our highways but we all know that their presence causes a huge drop in revenue, so don't hold your breath.

is Mise,
As long as we don't work on improving mentality we'll never get on top of it. Try to imagine 200 million Australians instead of 20 million. Scary eh ?

Improving mentality is the answer and one way of improving it is to allow people more responsibility and one way of doing that is to get rid of some of the ridiculous speed limits.
Another is to instill into the authorities some idea of real safety; as I've remarked before, highways (??) with broken centre lines in blind corners, ditto on straights with car concealing dips, crests with broken centre lines, corners with reverse camber

Then there are the Roundabouts with pretty vegetation in the centre that stops one from seeing entering traffic and where there is 'beautification' on the median strip with resultant reduced visibility to the point of danger.

One might also add to the multiple stupidities, the encouragement by the Authorities of the pernicious and dangerous practice of driving with headlights on during normal sunny days.

<< There is a slight problem, you will need multiple cameras etc., to record every thing at all angles. >>

Yes Is Mise, that is exactly what I am proposing.

<< Unmarked police cars and obvious police cars equipped with cameras etc., are no deterrent, nor are the police aircraft that can monitor roads. >>

They are of considerable deterrence value. If they weren’t, practically everyone would just ignore speed limits with impunity. But for the d!ckhead fraction of drivers, the number of police out there is so small that they reckon there is very little chance of being caught for speeding. And as for the things that the police don’t police, like tailgating and dangerous overtaking – the sorts of things that in-private-car cameras could record, well… the police are just no deterrence at all!

<< The only proven deterrent is plainly identifiable police cars driving along our highways… >>

Regarding speeding, probably right. And they are awfully thin on the ground, all-considered. This is why we need to empower the public to help.

This really is just the same principle as for Neighbourhood Watch and campaigns imploring us to report litterers.

<< …but we all know that their presence causes a huge drop in revenue, so don't hold your breath. >>

Yes. You really do have to wonder just how real this motive is. I just can’t see why the policing of road safety excludes public participation while for the other abovementioned things public participation is strongly encouraged. The only possible reason would appear to be the loss of revenue, as empowering the public in the way that I suggest could be very successful, and could therefore lead to a very large drop in the revenue from fines.