There is no benefit to a government to publish their own blockchain completely under their control.
If they want a digital currency, they can do so in a centralized way. Doing so has no need of a blockchain at all.
The purpose of the blockchain is to provide a decentralized consensus among the users.
Limiting fraud is a benefit.
There is nothing about a blockchain that makes it easier for a government to prevent the fraud of others.
The only thing a blockchain does is take control of the currency away from the creator.