Coloring shades of grey into our tax laws...
The current rule is that only the first sale or lease of a car generates a tax credit; in the case of a lease, the leasing company takes the credit (see http://www.fueleconomy.gov/feg/taxevb.shtml , under "Requirements").
Somewhere between tax fraud and the current rule are some legitimate scenarios we probably do want to encourage (like buying a few-year-old electric vehicle instead of a new one, or the same electric vehicle getting leased out multiple times), but these scenarios are:
1) Harder to monitor
2) Too long-term to be compatible with the short-term nature of these tax cuts, and government budgeting in general.1) It shows consumers that their gov't is supporting this. That's good for citizens to be aware of, regardless of whether you think this credit is a good or bad thing.
2) Ideally, it shouldn't matter but I don't trust car salesman to give consumers the best part of any deal. Consumers are generally not equal negotiators and I suspect sales people will pocket more of the tax incentive.
They can say the car is discounted to include the incentive but they may not apply the entire incentive to the discount. The more complicated a deal is, the less likely a consumer is going to get the better end of that deal.
That may be fine if you're favoring a completely free market but I prefer to side with consumers and favor protection when possible.
The residual value guarantee is pretty good though.
usually there is a separate entity that finances or leases the cars sold at the dealership, such as mbfs for mercedes benz financial services, gmac for general motors (defunct) etc
for tesla to offer the rebate directly they would have to setup a revenue split from the finance back end, or take a hit on the sales revenue, which is either difficult to get out of a bank, and not in the interest of tesla, respectively.
You aren't qualified for the $7,500 federal tax credit if you lease a vehicle, only if you buy. For many first-time EV owners, buying is a big leap of faith. It's a new technology and no one knows for sure where battery tech will be in 10 years. Many drivers would prefer to lease but don't get the tax benefits of purchasing, so instead they decide to stay on the fence.
Tesla just pushed them off the fence.