He’s not adding a VAT, he is replacing corporate and payroll taxes with a 16% flat tax. That’s a much lower rate of tax on businesses. Personal income tax s at a flat rate of 10% for everybody.
It’s a VAT. And a VAT is one of the most insidious taxes ever devised, as it hides the cost from the real taxpayers. The experience worldwide, with Europe as Exhibit A, has pretty universally been of such taxes introduced at a low level and then jacked up pretty quickly. Doubled up with a personal income tax, that’s how you get the “democratic socialism” of Europe that Bernie claims to want to emulate.