I agree with the doubts you both raise. $2000 seems so little to begin with, Iwondered if people would find it worthwhile an incentive, given metals prices are so high at the moment they might as well scrap an old bomb and probably get decent money for the metal alone. If someone is hanging on to a car that old, either they are poor (and unlikely to be looking for a new car purchase to trade-in anyway) or it has sentimental value.
In some cases, it's questionable whether encouraging a new car purchase is necessarily best for the environment, given all the embedded energy involved, compared to purchasing a newer, second hand vehicle. I understood the number of cars to be affected by this policy was miniscule as well ~200,000 nationally, so it sounded populist but ineffectual from an environmental point of view.
If the govt. wants to enforce people purchasing cars that meet lower emissions standards it might have been better to keep raising the bar at periodic registration inspections and gradually phasing cars of a certain vintage out completely within 2 to 5 years say – without this price tag.
I also wonder if there are other measures that continue to be overlooked through the tax system. For example, why is it that so many Australian are purchasing 4WDs these days, when all they are doing is taking a couple of passengers around in urban driving? These cars are huge, heavy, and have features well beyond the needs of city driving. I learnt how to drive 4WD Land Rovers, and used to own a Nissan Ex-Terra, both in conditions that warrant that kind of vehicle. But here, I'm quite happy with my economical little 4 cylinder 2WD.
Unless one works on a rural property or out bush on a regular basis, the features of 4WDs are largely wasted on city drivers. People who need such features to earn their income eg., farmers, rural workers, parks and wildlife rangers etc should be able to claim a rebate upon such proof via their tax returns, but everyone else should be paying a luxury tax on these cars at time of purchase. The plethora of luxury 4WD I see on Australian roads in recent years seems to signal a car manufacturing industry overservicing a misplaced consumer demand for an image out of proportion to the use of the vehicles – with ramifications for their impact on the environment in manufacture, use and end-of-life disposal.