Those schemes don't usually depend on knowing what each particular citizen bought; the tax is imposed on the product, not on the person, so you'll pay it even if you use a perfectly anonymous currency.

That said, I do agree that governments care about the contents of the purchase; around here, all sales must be invoiced with certified software, and a copy of all invoices issued must be delivered monthly to the IRS by businesses. As the buyer, you can opt to remain anonymous, but they're trying to push people into not doing so.