From the rules[0] that are mentioned in the article:

> On 21 October 2020, the Commission adopted a new strategy on open source software1, encouraging the use of open source software by the Commission, the Commission's contribution to third-party open source projects and the sharing of Commission software as open source. In that Communication, it was stated that, wherever possible and appropriate, the Commission would share the source code for any computer programs where it holds the intellectual property rights on behalf of the Union.

But:

> This Decision should not create any obligation for Commission services to share Commission software under an open source licence nor any right for third parties to require Commission software to be made available under an open source licence. The Commission should remain free to decide whether to share Commission software or to license it under a proprietary licence.

[0] https://ec.europa.eu/transparency/documents-register/detail?...

Managers climb higher in the hierarchy and get salary increase according to how high the budget they manage is.

There is therefore a consistent effort in all the units of all the Directorate Generals to ask budget for new projects, and find a plausible excuse about why an existing solution cannot be used, and a new solution needs to be built from scratch.

Then, once this is built, it is common practice to initiate a new project to throw away the solution and re-do it from scratch, again using an excuse reason like adapting to more modern technology, or providing better performance.

P.S. The European Commission is composed of 33 Directorate Generals (DGs), each of it responsible of a specific topic. One Directorate General, called DIGIT, is in charge of providing IT solutions to all the others. However, each Directorate General has its own IT department (called 'Unit'), developing solutions on its own, rather than using what is commonly available at DIGIT, or already created in other DGs' IT unit.