And because most people are not involved in calculating their regressive taxes, it is fairly poorly understood. So we will concentrate on explaining regressive taxes, and how the two combine to make up our system, and most systems of taxation. All known functioning systems of taxation have a balance of progressive and regressive taxes. In a progressive tax, the more you earn, the higher your tax rate. In a regressive tax, the less you earn, the higher your tax rate.
Progressive taxes soak the rich, regressive taxes soak the poor.
An example of why sales tax is regressive. Let's imagine two frugal traveling salesmen. Poor Boy has 5 times the tax bite, or rate of tax on a car. Rich Boy hardly feels sales taxes. Sales tax is NOT a flat tax.