[ncruces]

In my country, segments more prone to “informal” sales (SMEs, cash transactions, limited incentive for paperwork), have reduced VAT (final sale has a reduced rate compared to many supplies), and the customer can get some of that VAT back as an income tax deduction if they demand to be invoiced.

The advantage of this, is that if you have to have accounting for sales, you'll probably have accounting too for labour, and you'll also pay income tax, social security, etc.

[PaulDavisThe1st]

In my US state, vendors & service providers are quite open about "if you pay cash, I will not charge you the Gross Receipts Tax" (GRT is New Mexico's weird attempt at something vaguely like a cross between VAT and a sales tax).