Unfortunately the ISO certification process for office document formats was subverted by Microsoft to require their OOXML formats instead of the ODF (Open Document Format) that was being prepared for this role. And then they continued by not implementing the certified format correctly in Office anyway.

As a result it's virtually impossible for any law-abiding, taxpayer-answering government to argue for adopting ODF over OOXML

It's also impossible to find any other software that supports existing documents, because Microsoft introduces differences from the spec on purpose and any software that tries to stick to the official OOXML format can't process them 100% correctly.

Any government that wants to wean itself off Microsoft documents would have to first conduct an investigation, explain why ODF is the better format, demonstrate that Microsoft doesn't follow their own spec, then accept the fact they're gonna partially lose their existing documents if they move away, and only then they'd be able to start the process of looking for ODF-supporting software and companies, and convert their docs and processes.