I realized I forgot to include a personal exemption ($3950) for the 89k theoretical case. The 89k income with standard deduction and personal exemption (6100 + 3950) brings the tax bill down to $15,593.75 or 17.52% versus a bracket of 25%. If he/she contributed to 401k, paid for employee healthcare, or had more exemptions it would be lower.
Between my wife and I we have: mortgage interest, property tax, state tax, healthcare, 401k, 3 exemptions (including child), Dependent Care FSA, regular FSA. All of this totals to $75,779 worth of deductions/exemptions/pre-tax off the federal taxable income. Even though we hit a bit of AMT we still aren't higher than 17% effective federal tax rate.
Tax code seems kind of dumb if we can pay less effective federal tax % than someone with significantly less income. The tax code could probably use simplifying by eliminating 401k/FSA/mortgage interest benefits to pre-tax/deductions.