If that were true, then all these government IT projects from these infamous consultancies would all come in-time and under budget, but that's never the case, because every government wants things completely different than the other government, so it's never a just a copy-paste, fire-and-forget type of job.
corruption requires costs you cannot verify after delivery. for construction it's the exagerated foundation which they only actually deliver what's needed and pocket the difference. for software it is the hundreds of rewrites that may or may not have happened and are now in the past.
No, that is plain fraud. Corruption is paying so that no one notices or cares about the the costs that can't be justified after delivery.
If there was a government IT office, it could build this in house, and after the initial investment in building the base infra, re-use it almost for free in every government agency in the same country. In the context of the EU, they could even make moves to share this code with other governments, passing on the savings there as well.
I mean sure if it wasn't for the fact that those bigger players are going to be looking at this as a way to print money.
The problem of course is that using someone else's proprietary, closed-source code makes you beholden to them. That's a problem for consumers but it's an even bigger problem for sovereign nations. Would be a great outcome if greater awareness of this problem lead to more state resources being invested in open source alternatives to proprietary software.