[...or the taxing authority would have to spend far too much of their budget to collect it (like it does now).]
You're kidding, right ? Most Americans believe themyth that the only cost to collecting the income tax is the $12B in the IRS budget. A collection cost that is 1/2 of a percent has not dissuaded anyone that I can see.
If you start with the basic truth that no nation ever taxed itself into prosperity, you'll see how the lowest compliance cost (in real dollars, not percentage) is of substantial benefit to the taxing authority.