According to [1] Warren Buffett's house is worth .001% of his total wealth, at $652,619.
And for Warren Buffet to pay sales tax proportional to someone with $500,000 in assets buying a $50,000 car, he'd have to buy the world's most expensive car - a $5 million Koenigsegg of which only 3 were ever made - 1700 times over.
[1] https://www.businessinsider.com/warren-buffett-modest-home-b...
It's a bit like a straw man fallacy.
It happens a lot less often on HN though in my experience.
Right after the bit you quoted I noted that WB buying an expensive car doesn't even things out.
The idea of sales tax as a replacement for income tax isn't new or lacking rigor. Over the years it's had a lot of support from both economists and politicians. The math, at least on the surface, does work.
Personally, I haven't spent enough time looking at it to have a lot of conviction one way or the other about it's viability.
But it's an interesting idea that isn't invalidated by comparing cars.