It's basically a war between the big broadcasters, who want to transmit anyway they can to make the most money and get the most eyes, and the government who can't quite ignore the fact (even though they are trying) that they are supposed to look out for their constituents. Analogue TV is supposed to be switched off about 2006 here. There is still some uncertainty as to whether that will happen because take up of digital has been much slower than expected.
Digital TV is a godsend if you're in a ghosty area or merely have poor reception, but then so is cable (both major cable providers in Au must redistribute the free-to-air channels). And signal boosters solve a lot of ghost and reception problems, too. At the moment, digital TV gives you multi-channel audio and widescreen which means they'll get currently generally get only the enthusiasts and early adopters. (And I discovered a few days ago some friends who intensely dislike the fact that widescreen DVDs force their 4:3 TVs to show the content letterboxed.)
Wade.