"Plenty of Govts and their agents tell nothing but the truth on many topics, though."
The question stands
In all manner of mundane, run-of-the-mill, pedestrian ways, Govts tell the truth;
Environmental; reporting studies of bird and animal populations, analysis of flood plains, of coastal erosion, of landslip, of river flows, ship and boat registration, vehicle licencing, town planning and building, etc. etc.
Population; overall numbers, splits by county, city, town and village; splits by age, by sex, etc. etc.
Schooling; overall numbers, splits by private and state-owned, numbers of pupils, splits by sex, etc. etc.
In criminal law, the presumption is of innocence until proven guilty. Guilt by association with another (allegedly) guilty party does not make a valid case. Even if you prove Govt lies about something, somewhere (balance of payments, unemployment stats, number of COVID cases or vaccinations), that is not an automatic proof of lies with regard to space exploration, global mapping, or any of our hot topics here.
Mistakes and errors of incompetence do not equate to "lies".
Do you presume the Govt innocent until proven guilty?