So IT IS technically possible to gather the labor force to build the project in house, it just isn't much political motivation to do so when you have lobbyists swaying leaders in the other direction, and the investigative journalists and voters are too tech illiterate to understand this type of grift because when the government pays a billion Euros for a bridge or a tunnel and after 10 years the bridge or tunnel is not there, everyone notices and someone needs to go to jail or at least loose their job in politics for that obvious theft.
But if you spend a billion to consultancies on a government IT project, and it's an offshored clusterfuck that barely works and could have been done better by a local shop for 1/100 of the cost, then the journalists and taxpayers have no clue they've been robbed blind because nobody understands the nitty gritty and costs of SW development, and unlike bridges and tunnels, the public can't see the source code in the open as they walk to school to see that there's nothing there, which is why government IT projects has now become the best and easiest way to funnel taxpayer money into private pockets.
If you want to attract good talent, there are successful models out there now, but you have to start by paying them way more than the average government salary. But the contractors throw lobbying money at these things and try to stop them every step of the way.