The State income tax deduction is a de facto Federal subsidy to high tax states.  If your state has a sales tax,  and no income tax,  you get zero benefit for subsidizing CA and NY.  Or Oregon.  

The under represented tax by the Feds is SSI.  It applies to first $127,200 in wages.  7.65% by employer and 7.65% by employee.  After that limit,  there is only Medicare tax to pay which is 1.45% by employer and 1.45% by employee.  $200,000 and over of salary and wages,  and the Medicare by employer stays the same and employee is raised to 2.35%.   All of which says the big public employee earners are getting a pay raise when their overtime and/or salaries exceed $127,200.  Their taxes  go down by 6.2%.  Yet the poorest who earn an hour of minimum wage have to pay the SSI and Medicare taxes on their first dollar and all after to $127K.   Zero forgiveness. That is regressive.  Even though they will most likely collect more than they pay by a huge margin,  if they live long enough to collect