A metal one, of course, could be hammered out straight and used again- as so many of us have done...no doubt multiple times

Of course, they cost more (at least it's a relatively nominal one-off cost). But it's a victory for common cents over common sense, even worse when it comes from Government.
Even worse, consider this: someone has a deadly accident (let's say a single vehicle accident, SVA) in the country. Car runs off the road, rolls, hits tree, bursts into flames and is burnt out. A plastic number plate is gone- shattered and burnt. A metal one- usually steel still, aren't they- has a good chance of surviving and therefore quickly assisting with IDing the vehicle and its owner, perhaps driver. The ID plate and/or VIN and/or engine number, as we knwo could be different (changes) or burnt out if they're alloy/aluminium. registration is the primary way of IDing a vehicle.
All VH-registered (for Oz) aircraft are required to carry a small (brass I think) plate in the cockpit with the identifying registration of the aircraft for this very reason. It's usually on the dash too, as you have to ID yourself on the radio by callsign and it's nice to have it there when you hop between aircraft! And we've all seen how aircraft can crash and burn. It's no bigger usually than (say) three keys on your standard computer keyboard. Brass because it will withstand a ferocious fire (steel won't). That's all it takes.
Plastic number plates should be banned, in my personal opinion.
(Rant off)
