Not to mention secure and tax free. Government will surely hate that 'tax-free' privilege of bitcoin users.
And others still want Bitcoin to be used worldwide and main currency of the whole world to the point that bitcoin must replace fiat. They didn't know that if that's happen government will put some taxes in terms of using payment system that accepts bitcoin.
And how do you expect government to put tax on bitcoin transactions?
The transactions are all in blockchain and the government has nothing to do with it. Even if someone sends 9999BTC, the government has no control of it. Unless they make a law against bitcoin. But bitcoin users are anonymous and can be more anonymous by using a VPN.
Now that I mentioned that even if they put a law about bitcoin, we can still go anonymous, the only thing they can do to completely stop people from using bitcoin is to totally shut down the internet in the whole country.