They do it by lowering the base rates.  Broaden the tax base so that more income is taxed, but tax it at lower rates.

This plan goes in the right direction, but the problem is that it's doesn't go nearly far ENOUGH.  They should really eliminate ALL tax breaks/deductions/credits, and lower the base rates accordingly.  Wanna buy a house?.. Fine, but quit making other taxpayers subsidize your mortgage via the interest deduction. Same with charitable donations, and child credits, and EITC, and every other tax break/deduction/credit. Get the government out of the business of manipulating citizen behavior via selective and unfair tax deductions. What you choose to spend your money on is your business, not the government's (as long as it's something legal, of course).