Why is it better that 5 private companies make the same product and compete against each other in marketing? Why should the government buy a product from them, and spend lots of money to tailor it to their needs, without even owning the finished product?
Where do governments get their money from? Taxes on economic activity. The more economic activity the government performs itself, the less opportunity there is to raise tax revenue.
Take this through to its logical conclusion and you have the government owning farms, making food, making its own steel, building its own cars, etc. with a corresponding loss of revenue-raising activity in the real economy.
> Where do governments get their money from? Taxes on economic activity.
That may be true of local/state governments, but it isn't true for currency-issuing governments like the US. I'm not as familiar with the EU monetary system as I haven't read as much into it.
From my understanding, most European governments purchase American or other foreign-owned software, which often does not contribute to tax revenues in the countries where it is used.
Software licenses are certainly a major expense for all levels of the Danish government. (Cloud infrastructure, too, increasingly.)
They've started complaining, especially since prices have been going up, but while there's rumbling underground, we've yet to see any real movement away from Microsoft.