If you stop to think about it, there are only 3 possibilities: 1) Taxes are perfectly calibrated to exactly what they need to be. 2) Taxes are less than they need to be. 3) Taxes are more than they need to be.
Perfect calibration is nearly impossible. So that leaves 2 and 3. Which do you think is more likely of a corruption-prone organization that takes income through the implicit threat of physical violence?