Right now, the standard deduction is $11,600, $8,500, or $5,800, depending on filing status. This makes taxes more complex than they have to be, and allows High Incomes to benefit disproportionately from deductions.
The threshold represents the assumed level of public good; if the person exceeds that amount, they are rewarded for their charity, if not taxes will be simplified. This fails in two ways.
First, taxes are not simplified. High Incomes are able to deduct so much, that their taxes automatically become the realm of specialists, costing the rich more to complete, and costing everyone more to audit.
Second, High Incomes benefit far more than those who take a lower income, even if taking a lower income produces more public good than the gas and milage deductions of the High Income.