I am Dutch and I am glad they finally started to do some open sourcing. I have worked at different governmental bodies and have been promoting open source for some time now. But as a simple 'added hands for hire' I never got any response to my pleas. I guess it's typical Dutch that we are one of the last to do so.
The government still plans to place the authentication system of all Dutch citizens in USA hands.
And interestingly, code.overheid.nl runs from a residential ip address.
Also worked for the dutch government for the last 5 years. All or most of the projects we did have been open-sourced on github over the years. Currently there are plans to move them to code.overheid.nl I think, though I no longer work there currently. (I was the github org-admin for the department)
I am living in Spain, and from my point of view, Netherlands is one of the ones doing the most for FOSS in Europe today! It sees much faster real-world adoption of FOSS in ministries and municipalities than other countries, the government seems eager to fund FOSS (again, compared to other countries) and generally be welcoming to the ecosystem. Browsing around, there seems to be lots of FOSS projects funded by money coming from the Dutch state.
Kind of interesting how the perspective is so different from the inside! Maybe it's the typical "the grass is always greener..."?