My experience with the tax credit having used it to buy a Volt was I never really saw the money. I financed the full price of the car minus my normal down payment (vs taking out an additional $9000 from somewhere to offset the state and federal credits) then I applied for the tax credit when I did my taxes and applied for the state rebate. Got $9000 back, but when I sold the car a few years later, that $9000 was added to the normal car depreciation amount. Which was a huge hit percentage-wise on a $35k car. So I didn't really save $9k in the end. That is the biggest reason why used EVs are soooo cheap.
Now, the Tesla dynamic will be slightly different since the credit will expire at some point. But there is an argument to be made that the manufacturers are the only ones reaping the benefits of those tax credits.