Income taxes are adminsitered locally. In any case, each state is going to have to vastly increase their tax departments. How will a state that doesn't have jurisdiction in other states going to audit companies who are in multiple states ? Keep in mind that someone needs to check all sorts of off the book transations to be sure they are not bypassing the tax. That takes manpower and it takes folks pouring through transactions, courts, etc.
In what universe? They're collected locally (most of the time), but are administered centrally from the IRS in Washington. Sales taxes are administered within the states themselves, and at the point of sale.
In any case, each state is going to have to vastly increase their tax departments.
Also incorrect. 45 states plus Washington DC already have sales taxes and are currently monitoring those points of sale. If anything, the reduction in complexity in the sales tax code would reduce, not increase, the enforcement effort. In any case, part of the sales tax rate goes to the business and the state as compensation for their efforts.
How will a state that doesn't have jurisdiction in other states going to audit companies who are in multiple states ?
I would expect that each state would audit the points of sale within their own borders. They wouldn't need to audit beyond their own state lines, since the tax is enforced not at the corporate level, but at the point of sale.