Sales taxes are not particularly regressive; they're not progressive.
Opponent of general sales taxes correctly point out that lesser income earners must spend a greater proportion, and higher income earners need not, and generally do not spend their entire incomes for products that would be subject to a general sales tax. Lesser income earners generally do spend a greater proportion of their incomes for such items.
Truly, the poor have little or no discretionary income and the wealthy have more such discretionary income. The poor of necessity generally must spend the greatest comparative proportion of their incomes for such products.
The expenditures of the wealthy that would not be subject to a general sales tax, are currently items that generally now reduce their taxable incomes. Proportional to their individual revenues, their expenditures that would be subject to a general sales tax are no less, and I suspect exceed the proportions of their revenues subject to our current federal individuals' income taxes.
But for those that do not pay income taxes, a general sales tax would be a regressive tax.
I'm a proponent for replacing a significant proportion of taxes levied only upon wages and payrolls, and replacing those revenues with a general sales tax. FICA is the most regressive of federal taxes.
This proposalwould net increase tax revenues for funding Social Security, Medicare, net purchasing powers of USA employees and their dependents; it would to some extents reduce effective federal taxes upon USA's enterprises and to greater than a proportionally similar reduction of USA's corporate taxes, reduce their products price disadvantages to foreign competing products both within and beyond USA borders.
Respectfully, Supposn