This is so unacceptable yet happens so often. Here in the Netherlands the government has several projects that failed with costs amounting to hundreds of millions. For sums as these any Organisation can just setup a more capable development company that could handle all of the internal projects and its developers could be top of the line.
The thing is, yes you can set up a new company and make a new product from scratch whose requirements are exactly defined by you and after a few years of work they'll have a working product. Then what? You'll still be running the same software in 10 years, are you going to keep paying an entire company's worth of employees during those 10 years so they can hang out and be ready to implement all the changes you'll eventually need, to fix bugs and provide support? The costs of that would be far higher.
Most non-enterprise people don't get it (as seen in this thread where most people are only taking into consideration the cost of development): In a software suite's lifecycle, the initial implementation cost is nothing compared to the total cost until sunset.
Application lifecycle management (or product lifecycle management in a broader context) is a hugely important thing for a corporation that plans on existing for more than a couple years.
There is never just one project. So these employees can keep improving the original project and create new ones. Do you think these consultants will do all that maintenance? Many projects fail before release and others just last for a few years. A government owned software department would be a great way to save money and improve all aspects of the application life-cycle.
This specific case, though, is totally acceptable : Lidl is a company in a market with great opportunities for competition. If this decision was a waste of money, a smaller , SAPless company can come and eat their lunch.
The Dutch government is a very different story. Until we have a few parallel governments between which we can easily choose , without having to uproot our entire lives, it is a pathetic waste of tax payer money. I dream sweet dreams of accountability and proper incentive structures for government and public servants.