That's actually not the main problem why governments don't want full adoption of Bitcoin.

Each government in several countries certainly has their own research and will have different problems.
It cannot be generalized that every country has the same constraints.

Banks are indeed a barrier to adoption, as traditional money is still the primary means of transaction.
But the main reason why adoption cannot be done is the application of Blockchain Technology, which cannot provide freedom of space for the government so that everything can be tracked, and the government does not have any control over it.

Governments prefer centralization, whatever they must be able to control, otherwise there will be strict regulations imposed.