Earlier quoted context omitted.
This is my favorite proposal to date. Sales tax applies equally to a pencil and a yacht. It also encourages savings at lower income levels.
A sales tax is the ultimate regressive tax. At the low end, you don't have much to save anyways (you need to eat!), so you are spending your income and getting taxed. At the high end, you can save a lot more since you make more. And you can always fly off to Hong Kong for a weekend to buy things (that is what happens today in China which has a high VAT/import tax).
I have come to find that "regressive" moves the goalposts. It sounds as if the rich pay less. They don't pay less; they pay more. They just don't pay more when dividing taxes by their total income. I've never heard a convincing argument for why that formula is the ultimate benchmark.
And anyway, virtually all sales tax proposals have some per capita rebate/basic income, and that can be tweaked to make it as progressive as your heart desires.