That is because they don't read freerepublica, I posted it here that it would be considered taxable income. In a country that taxes SSI, nothing else is possible.
You earn it- pay income tax on those earnings.
Government "gives" you $4500 of your tax money back, which you have to claim as income which you pay taxes on yet again.
PLUS, You pay sales/state taxes on it.
Plus you basically give them your clunker for basically nothing, which I imagine either the dealer or government gets whatever salvage value it's worth.
If the dealer, the salvage value is deducted from their 4500 reimbursement for fronting you the clunker cash.