> just so that a few people can feel like they are evading government supervision. (Hint: they are not).
It seems like you're conceding your own point here. If you live in a mansion and drive a Ferrari and claim you only make $15,000/year to the IRS, you're going to jail like Al Capone.
Whereas what cash allows you to do is keep anyone from knowing every little thing you buy, which is irrelevant to income tax which by then you've already paid and also irrelevant to sales tax which is collected by the seller even if they don't know who you are.