While technically rich people consume more than the poor in absolute numbers, they consume a smaller percentage of their income than the poor, so a consumption tax is inherently regressive, taxing rich people less.
If you wanted to tax richer over poor, this is not an efficient way to do it at all.
It is also a pretty distortive tax, and it creates smuggling, robbery, and disproportionally punishes those that consume those products and are also on the poorer spectrum.
Even still, there is no sales tax rate that ends up charging wealthy people anything meaningful. Roughly speaking, the savings rate of wealthy people is so high (and therefore 1-that as spending rate) and everyone else basically spends all their money, such that you need exorbitant taxes on “stuff only rich people would buy”.
Zucman and Saez have a decent figure for this, which this article in the Atlantic includes as a high resolution version [1] or a non paywall one at [2]. People quibble with the details here (particularly post taxes and transfers like social security), but much of the income and much of the wealth is in the top 10%. The bottom 90% basically saves nothing,
and while many at the true bottom decile / quintile spend it only on the goods you would exclude, you still end up with “we can’t tax wealthier people, without being regressive” for most of the middle.
For example, car payments, home sales, electronics. These are all “normal” things for most people, so unless you want to raise taxes on the bottom 50% or so (who currently do not pay much in income taxes), you have to exempt a much wider variety of goods.
What does that leave you with? Yachts? Cars over a certain amount? Houses over a certain amount? It’s not impossible to figure out how to do it, but you then get to pile on import taxes (“Fine. I’ll buy my yacht in the Bahamas and sail it here rather than pay 10x in taxes”) and so on.
Fundamentally, in designing a taxation system, you’re deciding how to fund the government and redistribute wealth. It turns out that spending, even of non basic goods, isn’t a good proxy of what an individual can afford to contribute without noticing. Income isn’t perfect, but spending is actually pretty bad.
This is not very convincing. Top 1% save 40%, so they spend 60%. In order for a consumption tax to work, it would need to be in the 30-40% range. So you'd be capturing 60%*35% = 21% of income. Currently incomes tax is 27% of income for the top 1% in the US.
Add on top capital gains and you're collecting the same or more than you are now.
But that 35% sales tax is a huge increase for everyone at the bottom, that’s the point. The bottom 50% pay “no income tax”, spend roughly 100% of their income, and would have their taxes go up by XX * 35% in taxes under this scheme (where XX depends on what you put in the exemption bucket or not). There’s probably data from Washington state or similar on the distribution of purchases, but you can’t just stop at “35% would work” since you have to exempt more things if you goal is not to be regressive.
P.S. I don’t think when people call for “just sales tax” they also mean “oh and sure plus capital gains” (besides, this would just shift back towards dividends).