Really, this article is just a whinge. I'm an Australian. MyGov is fine, I interact with it as a citizen regularly. Government needs to outsource implementation of this kind of stuff because it's extremely hard to build software teams and manage their performance in permanent government roles. And those costs are reasonable - particularly for anyone that builds teams of software engineers and knows what aggregate team costs are like in Australia.
The hard part of the MyGov platform is the inter-department stuff, and I don't think that's a software issue, that's bureaucracy.
MyGov isn't perfect, but it's fine.