At this point, I don't really consider OSM an OSS project, but an infrastructure. It has small value for everyone, but all combined usage, it has immense economical value for the society. All alone, it's not really useful to end-users, but it can help a lot of businesses that couldn't exist before it. Maps are already considered infrastructure, since they are already made by governments! The only missing part to say…
The best way to contribute is to openly license government datasets, and many such datasets are already in use and being used to improve OSM (and often problems are reported back, resulting in fixes in official datasets!).
Government official editing directly would be in many cases more harmful than useful.