Other countries had it before Melbourne and rolled it out smoothly. Hong Kong launched theirs in 1997. 11 years prior. Melbourne could have easily bought it off the shelf. Melbourne was not early by any measure
eg Tap on a bus, tram and train in Melbourne, get off in Wangaratta and tap on to a bus there.
There was going to be something like 29 zones, and all the requirements / edge cases / mucking around sent the cost through the roof.