Melbourne's Tram Holdout and Decline

In 1959 a flight to London took days and cost half a year’s average salary.  But things were changing rapidly. The invention of the Concorde meant that you could fly from Adelaide to London in just under seven hours.  Travel was getting faster and many expected we’d be routinely zipping around the world and travelling to other planets in no time. But now, aside from planes, most of our transport is not much faster than it was back then, so why are we still so slow?