1. In most cases you can get around that issue by leasing.
I don't mean to be rude, but (2) if someone doesn't have $7500 in federal tax liability, they shouldn't be buying a new car. (3) Even retired people should be able to realize enough capital gains to create $7500 in tax liability. (4) If not, save your money and buy a gently used car. Tons of great deals on used EVs.
(1) True - if you want to pay, over many years, multiple down payments and monthly lease payments!
(2) Tax liability is usually associated with income. A $7500 tax liability suggests an income of around $100K or higher depending on deductions. You imply only higher income people should purchase new vehicles and the rest should buy gently used vehicles. There might be some wisdom in that thought but the buying public, automakers and financial institutions might take exception.
(3) Retired people - of which I am one - have varying incomes too and we have to also plan for much higher medical costs as we grow older.
(4) Your last point fits me, a retired person, perfectly. When the Spark EV first came out, I choked on the price - too much, even with the tax credit, and I did not want a car payment. In 2015 a friend of mine leased a 2015 Spark EV 2LT and told me about the special lease offer GM was having at the time. I found my 2015 Spark EV 2LT at a dealer 70 miles from my home and leased it for 3 years. State, County and electric utility EV incentives paid the lease in full for 3 years. Essentially I had a free new car for 3 years. 2 Months after I leased the 2015, I purchased and paid for a used 2014 Spark EV 2LT in factory-new condition and with only 1500 miles on the ODO for $13,500 (includes a $500 utility EV incentive). 2 weeks ago I purchased and paid for a 2016 Spark EV 2LT, in factory new condition and with only 6700 miles on the ODO for $11,200 (includes a $500 utility EV incentive) . This vehicle will replace my 2015 when I turn the 2015 in at the end of May next year.