Governments and international organisations tend to stay with whatever system family they have been using since they first switched over to the world of computing. Call it a form of inertia, if you like, or a grim comfort with what is familiar.
Moreover, it takes quite a while for them to internalise - or accept - that these systems need to be constantly upgraded or updated. For that matter, their audit systems and budgetary systems would have been predicated on the idea that once monies had been ear-marked for a particular project, and subsequently spent, that the project has been dealt with.
The idea that such systems are on ongoing expense is something it has taken many organisations, both public and private, quite some time to get used to.
In any case, no, I'm not surprised that XP is still in use. I remember Lotus Notes (which was perfectly dreadful) were still in use in one public body where I worked, long after Word was the standard which everybody else used.