Instead of Govt intervening locally, what if mayors ran the world?

Back in 2014 Benjamin Barber incited, and excited, a lot of comment by suggesting that things might be much better If Mayors Ruled The World. Of course that would depend on what Mayor you choose and I am sure a number of New Zealand  towns and cities  would make  a variety of  responses to such a suggestion.  
Yet we should not be so quick to dismiss.  Barber’s focus was on how mayors were able to successfully tackle a social problem by forming their own sub-national networks, collaborations and responses.