> Rather than, as you suggest, taxing every dollar that is spent exactly once (thereby ending up with a VAT), you could instead tax every dollar that is earned (by a real person) exactly once.

One of the problems with income tax is that there are a lot of things you don't really want to tax. For example, suppose you don't want to tax childcare. With VAT, you simply don't require childcare providers to collect VAT. With income tax, you need every individual taxpayer to file a tax return at the end of the year identifying how much childcare they paid for, and they have to accurately predict ahead of time how much that will be or they may overpay or underpay their taxes.

It's also an invasion of privacy -- you end up having to tell the IRS all about your life in order to get the tax deductions, instead of just not taxing those things to begin with.

Meanwhile there are a lot more individuals than businesses, which increases administrative costs and overhead.

If it's all the same in the end anyway then why choose the wasteful complicated invasive one?