Comment by thorel

You are right: the scheme relies on a sequence of cyphertexts being independent (or at least, appearing to be independent to someone who doesn't know the decryption key). However, this property is automatically guaranteed if the government wants their scheme to be secure against an adversary who doesn't know the decryption keys (for example, another nation-state). This follows from the definition of "semantic security" which is the standard security definition of encryption schemes.