Government do not support the use of bitcoin because they have no control over it and it pays no taxes to them. They give some penalty to prevent the generals using it. As a result many users are at risk and have fear of getting caught.
it is very difficult indeed to collect taxes from bitcoin, since bitcoin users are not only from one country but across countries and even the world and no limitations or transactions are going on, the government certainly loses income from conventional financial transactions that usually happen because many users switch to transaction blockchain