On top of that, said lack of knowledge is a stated goal of all privacy-focused browsers. GA-blindness is an implementation detail of these policies. Any method the government could use to accurately track that information is effectively a bug in need of fixing from the POV of the browser's developers.
The most practical answer is, as was posted by someone else here, the government spec'ing to a standard instead of a set of browsers, which it really should be doing in the first place. The mere fact that the current setup means that the government accidentally makes and/or breaks winners in that space is justification enough.