The "so called" poverty level is what screws up the math on how it effects everyone.
My Mother is 80 yrs. old, gets about 18k in SS and a small retirement. She pays zero in taxes now, but it takes every dime of her 18k just to scrape by now. After the pre-bate is figured in, she would be taxed 23% on aprox 6k. thats money she dont have.
Also; anyone that has saved some of their "aftertax" money now, would get to pay taxs AGAIN when they spend it.
The fairtax has its winners and losers, and retirees fall in the loser category on this one. That maybe the toughest sale of all for the fairtax.
You miss what many people do in that everything your mother spends now (when she "pays no income tax" in your words) she is actually paying what amounts to a hidden tax on everything she buys in the form of higher prices boosted by the effects of business income taxes and compliance costs.
This is not an optional tax and the buyer of things presently cannot escape from it whereas with the FairTax you mother could probably with judicious purchases of used things instead of new taxable things do quite a bit better with the FairTax where the consumer controls when and whether he pays taxes.