Illustration: Matt Davidson It was a promise. Not the $661 million; that was just an estimate, but the promise to use technology smartly to minimise mistakes and avoid intrusions into people's lives. Evidence before the Senate inquiry sets out what actually happened. Employers' reports to the Tax Office aren't designed to mesh with Centrelink data. They are prepared for a different purpose – annually, and after a delay. Attempting to automatically match them to fortnightly income reported to Centrelink will inevitably produce mistakes. The Tax Office could have told Centrelink this if asked but it didn't. It told the Senate its responsibility was limited to "the provision of the data".

Treasurer Scott Morrison and PM Malcolm Turnbull are shortchanging Victoria $6.6 billion, the Victorian government says Credit:Alex Ellinghausen Given that automatic matching of incongruous information would inevitably produce false reports, it was essential to have a working website on which falsely fingered people could set out the truth. The Prime Minister had set up an organisation to do just that, to "assist agencies with their digital transformations, to ensure that all services meet the needs and expectations of the user". Kathryn Campbell, secretary Department of Human Services, before a Senate committee hearing into the Centrelink robo debt collection. Credit:Andrew Meares But Human Services, the department that runs Centrelink, turned its back on the Digital Transformation Office.

"They were difficult to work with," its head Paul Shetler, told the ABC. "Very, very defensive. You know, nothing is wrong, everything is good, the house is burning down but everything is fine." When we stop trusting the government, we stop trusting its ministers. More than 200,000 letters were sent out to people that the mechanised matching program suspected of fraud, asking them to log on and clear up what was often the program's mistake. The union representing Centrelink workers says what those people often didn't realise was that unless they did much more than simply confirm their annual income the machine could instantly conclude they had been overpaid and declare them in debt. "It appeared to ask a few simple questions, however customers did not realise they had to delve further to enable them to type in their wages for every week or fortnight," said a Centrelink worker.

"We were actively discouraged from helping the customers," said another. "We were told to always refer them back to the automated system and only help them as a last resort. Directions have since changed to a slightly softer approach since the media attention." Then came the phone calls. "On answering this call, from a private number outside of usual hours without any warning of who it was from, the first question posed to me was: what's your date of birth," said the author of a submission to the Senate. "I was then told that I was effectively a criminal who'd committed fraud." Until recently such people were told to pay the debt (and the debt collector's fee) even if they were certain they didn't owe the money and had sought a review. Many paid. Human Services has been particularly cagey about revealing its estimate of the proportion of debt notices that are false, telling the Senate it didn't have the resources to work it out.

By letting machines get things wrong and demanding money it could have worked out wasn't owed, Centrelink reversed the usual onus of proof. The Commonwealth is required to be a "model litigant", to behave fairly in court. Until recently, it would have been reasonable to assume that's how it behaved out of court. It's required to keep personal information private. On its website, Human Services says it is bound by strict confidentiality provisions. Yet it has provided personal information about individual customers to its minister and to at least one journalist. It says it's allowed to, in order to "protect the confidence and integrity of the system". Many of those who have told their story to the Senate have asked for their names to be withheld. "I no longer trust that I would receive impartial and fair treatment from the department if I am identified," said one. "The department has demonstrated it is willing, and has the power, to attack critics by breaching their privacy without consent." Loading

When we stop trusting the government we stop trusting its ministers, especially if those ministers have been promising things we know haven't come to pass and by indifference have hurt our friends and family. Whether it is assurances that company tax cuts will really be good for us, or bright new ideas we are told will get more of us into housing or close the deficit, we will rightly be sceptical. Eventually we will become so sceptical that we will become impossible to win over, no matter how good the budget.