The problem with any income tax is that the cost of government is enbedded into the product/service. This adds a significant increase to the cost of goods and services products in the USA making our products more expensive. At sales tax eliminates that.
That assumes that companies will roll that embedded tax out of their goods and services if the tax is eliminated. I personally don't believe they will. Prices will remain where they are and in addition we'll get hit with a sales tax.
How much does the IRS cost to operate? How much would a new NRST "compliance" agency cost to operate? The difference, if any, would be the only reduction in government spending. How much would this "difference" save on the cost of a product or service? These are the only "savings" we could see from a NSRT.