The problem for large institutions is that they very often have specialized software relying on some American software or being American themself. More often then not that means converting large amounts of data from a propietary format into something useable by another software. The company selling the original software obviously does not want that to happen at all. Also both programs work in different ways, so data might have to be split in non obvious ways.

Then you need to retrain the workforce to use the new software, which probably does not work properly to begin with.

There are also often dependencies. Like Microsoft Office Add-Ins from third party vendors. They will not like going to Libre Office and it is likely not easy either.

Not saying it is impossible, but a transition takes years and is going to lead to some serious problems.