Because we do not really need to cross national borders to find Tax Havens. Crossing a state border is enough to shelter a lot of taxes.
https://www.theguardian.com/business/2016/apr/25/delaware-tax-loophole-1209-north-orange-trump-clintonAs it turns out , Hillary and Trump both have shell companies sheltering a lot of money from taxation in Delaware, and both are mail drops in this building .
This is not a huge coincidence this building has hundreds of persons and corporations using this as a tax dodge.
So Trump is smart to pay few taxes , and Hillary is also the same sort of smart.
IN Europe there were dozens of political careers interrupted when shell companies in Panama were discovered hiding the money of prominent people from taxes.
I don't see Americans getting that sort of outraged at Trump or Clinton.