Because... car loving idiots. In saying that though, Melbourne's trams aren't really that great except in the CBD. They are slow as hell, never on time, many have huge gigantic steps that are a nightmare for elderly, children, and if you have luggage and impossible if you have a pram or are disabled in a wheelchair. http://www.abc.net.au/news/2018-04-12/sydneys-original-tram-network-what-happened-curious-sydney/9610328