Why Has Growth in Income Inquality Led To Lower Taxes For The Wealthy In The US?

Everyone knows by now that the share of income going to the top 1% in US has grown significantly since 1975.  The US has experienced more growth in equality than that experienced by most large economies.  It is unique, however, in another respect.  Growth in income inequality is also correlated with lower taxes paid by the top 1%.  That has not been true in many other rich countries.  That raises a question about how to explain that result.  Conservative economists use supply side arguments to explain that result.  Lower taxes on the rich increase their productivity, which leads to an increase in their income.  Apparently, they refuse to work hard when taxes are high.  Its also possible that their higher incomes and lower taxes are better explained by greater influence over government tax policies and the effects of deregulation.  Changes in executive compensation are also an important factor.  Corporate executives and many money managers receive much of their income in the form of capital gains or dividends which are taxed well below the rates on ordinary income.  The US political system and the corporate governance have been redesigned to serve the interests of the elite.  The links between Wall Street and our large corporations is much more like it was in the "Gilded Age".  Both groups have also increased their influence over government through their lobbying efforts and by funding US election campaigns which become more costly to finance every year.  This does not surprise most of us.  The more interesting question is to explain why elites in many other countries have not achieved a similar result.  The American system is probably the model to which elites in other countries aspire.