It’s much easier to influence someone’s behavior by taxing their purchases than it is by taxing their income. It’s much easier for a person to choose to spend less than it is for them to choose to earn less. Taxation disincentivizes behavior, but we would far likelier to disincentivize spending than we would be to disincentivize earning income. Taxation should have as little influence on people’s behavior as possible, so an income tax is preferable to a sales tax.
Tithes come from the bible and were obviously based on income. It’s hard to imagine a biblical sales tax. Tithes make sense because they’re more or less directly based on your ability to pay taxes (other than allowances for how many children you might have to support). How much stuff you buy is a much weaker indicator of your ability to pay taxes.
.
And the injustice of taxation is compounded in taxing expenditures, which stimulate the economy, while not spending retards the economy.
The so-called Fair Tax is an exercise in absurdity.